Removal of target metal species

Abstract

The present disclosure relates to a product in the form of an aggregate which includes a bound metal species. The aggregate further includes a functionalised polymer, an organic additive and a precipi

Description

FIELD

[0001] The present disclosure relates to a product in the form of an aggregate which includes a bound metal species. The aggregate further includes a functionalised polymer, an organic additive and a precipitant. The aggregate is formed during a process for removing a target metal species from a solution, the solution comprising the target metal species, a solvent, and optionally non-target metal species. The metal species bound in the aggregate is therefore the target metal species described for the process. The present disclosure further relates to the use of an organic additive to modify the binding affinity of a target metal species in solution for a functionalised polymer. BACKGROUND

[0002] There are currently a number of known processes for the removal of charged species from liquid-phase effluents, including processes for the removal of charged metal species. Examples of effluent that typically contain charged species requiring removal, or whose removal would be beneficial both economically, environmentally, and (by extension) socially, are effluents in the metal finishing industry, the mining and mineral processing industries, the textile and battery industries, the catalyst manufacturing industry, and effluents arising from soil washing of heavy metal contaminated land and pharmaceutical processes in which metal catalysts are used. Metal ions are widely used in industrial processes, and such use means that they are present in the associated effluent streams.

[0003] As noted above, there are economic and environmental incentives for removing metal ions from liquid-phase effluents. Environmental incentives arise from the increasing stringency of discharge regulations. Metal ions are not biodegradable and can bio accumulate in the human body as well as in the bodies of other animals, leading to potentially deleterious effects on health. Economic incentives arise from the market value of specific metal species. At the time of writing, platinum group metals (PGMs), and gold can, for instance, have a market value of approximately £40 / g to £70 / g. Thus, it is worth recovering such metals from effluents provided a cost-effective and efficient method is available.

[0004] Removal and recovery of such metal species, particularly platinum group species, gold and silver, is further beneficial from a sustainability perspective. Industrial processes can be carried out on a large scale and thus generate a significant level of waste. When such waste includes precious metals, for example from the use of catalysts in the industrial process, it is both economic and environmentally desirable for the precious metal species to be recovered and ideally, recycled. Industrial processes use a variety of precious metal-bearing catalysts in the manufacture of drugs and other products. For example, palladium is widely used to facilitate cross-couplings, rhodium is used in hydroformylation reactions, and platinum is used to perform asymmetric hydrogenations. To improve the recovery and ability to recycle such metal species, it is particularly desirable for selective recovery methods to be available.

[0005] Known metal ion removal techniques have their advantages and limitations in various applications. A commonly used method is ion exchange. Ion exchange is effective to selectively remove small amounts of high concentration metal-ion contaminated water, but the cost and secondary pollution when regenerating resin are critical. Furthermore, the required solid-liquid, fixed-bed operation is complex, and the solid-liquid fixed bed operation is not effective in a single pass due to inherent mass transfer limitations between phases. Ion exchange resins are not therefore economical to rapidly treat high volumes of metal-ion wastewater. Electrochemical techniques are regarded as a rapid and well-controlled method to remove metals with fewer chemical additions and less sludge production. The drawbacks are high capital and running costs, limited selectivity and complexity of operation. Adsorption is an alternative method but the processes suffer from similar drawbacks to ion exchange and the balance between cost and effectiveness of physico-chemical adsorbents is difficult. Bio sorption has proven a promising sustainable removal method. The advantages are high overflow rate and low production volumes of concentrated sludge. The capital, maintenance and operational cost, are, however, high. The sludge produced by the bio sorption coagulation-flocculation method has good settling and dewatering properties, but the amount of chemical dosage, lack of selectivity and the sludge treatment / disposal are the main disadvantages to overcome. Finally, membrane filtration technology is a selective removal method based on size of species, but high cost, membrane fouling and low permeate flux are the limitations.

[0006] Processes for removal of metal ions are disclosed in, for example, Hankins et al., Separation and Purification Technology, 2006, 51(1), 48-56; WO 2016 / 079511; Shen et al., Separation and Purification Technology, 2015, 152, 101-107; Shen et al., Separation and Purification Technology, 2016, 159, 169-176; Shen et al., Emerging Membrane Technology for Sustainable Water Treatment, 2016, 249; Shen et al., Desalination, 2017, 406, 109-118; and Shen et al., Desalination, 2017, 406, 67-73. Such processes use polymers to remove charged species from solution, including the use of polymer-surfactant aggregates to avoid sludge production and provide an environmentally friendly way to remove charged species. The processes do not, however, involve the use of an organic additive which enables the binding affinity of a target metal species in solution to be modified.

[0007] There is therefore room for improvement with the above processes, particularly in the area of selectively removing a particular metal species from a mixture of metal species in solution. Selective removal is difficult, especially when removing a target metal species from a mixture of other, non-target metal species. Resin-based ion exchange technologies have previously been employed, such as in Colley et al., 2014, Chimica Oggi / Chemistry Today. 32. 72-7432, 5, but they have drawbacks as noted above. Performance of resin-based ion exchange technology is also limited by a relatively slow kinetic and hydraulic performance due to the heterogeneous solid-liquid interactions that are required for its operation, and by the corresponding complexity of fixed-bed process operation.

[0008] Other known processes for the selective recovery of target metal species also typically incorporate process steps which can be detrimental to efficiency and / or introduce complexity; both of which are undesirable for scale-up and the development of a commercially viable process. A solid absorbent (e.g., a solid functionalised polymer or functionalised silica) may, for example, be used alongside a liquid phase chelating agent as in Melek et al., Analytica Chimica Acta, 2006, 578(2), 213-219. For similar reasons to resin-based ion exchange technologies, the heterogeneous solid-liquid interactions can result in slow performance and corresponding complexity in the operation of the process. Other processes may need independent separation techniques in order to recover target metal species from a mixture, such as chromatographic separation (e.g. as in Kaur et al., Analytica Chimica Acta, 2007, 603(1), 44-50, physical separation methods such as liquid-liquid extraction (e.g. as in Le etal., Geosystem Engineering, 2018, 21(4), 210-216), or ultrafiltration (e.g. as in Dreimann et al., Chemical Engineering Transactions, 2016, 47, 343-348). In each of these processes, there is room for improvement.

[0009] An economical and sustainable technology, which increases the treatment speed and / or selective removal compared to ion exchange resins, is provided by WO 2021 / 053326. WO 2021 / 053326 provides a process to selectively remove charged species from industrial process and effluent streams. The process employs a polymer which is chemically modified via functionalisation, i.e. covalent bonding, to allow selective removal of the target ion. The process does not, however, involve the use of an organic additive and thereby have the ability to necessarily tailor the recovery to the polymer and / or target metal species in solution.

[0010] There is still a need for products and processes to effectively and selectively remove and recover metal species from aqueous waste solutions, such as from industrial process waste streams. In particular, there is a need to efficiently, selectively and economically remove target metal species from a solution containing target and non-target metal species. Such removal of target species is difficult, especially when a commercially viable process is required.

[0011] The present disclosure seeks to address these needs with the various aspects and embodiments defined herein. SUMMARY

[0012] The inventors have developed a product in the form of an aggregate, and a process for removing a target metal species from a solution, each using inexpensive, recyclable, and easily manufactured or obtained materials. The process is particularly beneficial for selectively removing target d-block metal species from metal mixtures such as industrial process and effluent streams including pharmaceutical waste streams. The process is not complex and is sustainable. Both the product in the form of an aggregate and the process of the present disclosure generally use materials available in bulk at low cost such as polymers, functional groups, organic additives, and precipitants. When formed in solution, the aggregate is selfflocculating and can easily be removed from the solution prior to facile recovery of the target metal species contained therein. The removal agents can also be recycled, minimising both cost and environmental impact of the process as a whole.

[0013] Each of the product and the process of the present disclosure include an organic additive which is a hydrocarbyl substituted by at least one heteroatom-containing group, the additive also comprising at least one group that binds a metal species. The inventors identified that such additive is beneficial in both the product and process of the present disclosure because it is able to modify the binding affinity of the target metal species in solution for the functionalised polymer.

[0014] The present disclosure is centred on the ability to modulate and optimise metal species recovery by strategically altering the nature and degree of functionalization of the polymer backbone, and adjusting the characteristics of the organic additive, so as to modify the binding affinity of the target metal species in solution for the functionalised polymer. Hence the improved efficiency of the process over known processes is not only influenced by the polymer’s functionalization as defined herein but also by the nature of the organic additive. The organic additive can, for example, be configured so that it binds and retains non-target metal species in solution, whilst the functionalisation of the polymer can be configured so that the functionalised polymer binds target metal species in solution (see e.g. Figure 4) and forms a precipitate on addition of a suitable precipitant. Alternatively, or additionally, the organic additive can be configured so that it binds target metal species in solution, and / or the functionalised polymer, whilst the functionalisation of the polymer can be configured so that the functionalised polymer binds target metal species (see e.g. Figure 3), the organic additive, functionalised polymer and target metal species forming a solution phase complex which then forms a self-flocculating aggregate on addition of a suitable precipitant. In all instances, the binding affinity of the target metal species in solution is modified for the functionalised polymer due to the organic additive. In this respect, the organic additive is not employed in the claimed process and product to compete with the functionalised polymer for the target metal species, rather the organic additive is employed to have a positive impact, namely a net effect on target metal species recovery by the functionalised polymer.

[0015] Furthermore, the organic additive is understood to be able to enhance the stability of the aggregate described herein. In some instances, the stability enhancement is relative to the aggregate without the presence of the organic additive.

[0016] Accordingly, a first aspect of the present disclosure provides a product in the form of an aggregate comprising (a) a functionalised polymer which is a polymer with at least one covalently bound functional group, (b) an organic additive which is a hydrocarbyl substituted by at least one heteroatom-containing group, and wherein the organic additive comprises at least one group that binds a metal species, (c) a metal species, and (d) a precipitant, wherein the precipitant comprises at least one hydrophilic moiety and at least one hydrophobic moiety, and at least one group that binds the functionalised polymer and / or the metal species, wherein the functionalised polymer comprises at least one moiety that binds the metal species.

[0017] A second aspect of the present disclosure provides a process for removing a target metal species from a solution, wherein the solution comprises the target metal species, a solvent, and optionally non-target metal species, wherein the non-target metal species is different from the target metal species, which process comprises treating the solution with a functionalised polymer and an organic additive to form a complex, and treating the solution with a precipitant. The organic additive is a hydrocarbyl group substituted by at least one heteroatomcontaining, and comprises at least one group that binds a metal species. The functionalised polymer is a polymer with at least one covalently bound functional group, and at least one moiety that binds the target metal species. The precipitant comprises at least one hydrophilic moiety and at least one hydrophobic moiety, and at least one group that binds the functionalised polymer and / or the target metal species. Each of the functionalised polymer, organic additive and / or precipitant may be as defined herein for the first aspect of the present disclosure. The target metal species will be understood by the skilled person to be the metal species (c) present in the aggregate, i.e. the first aspect of the present disclosure. Hence, discussion herein of the “target metal species” applies equally to the first and second aspects.

[0018] A third aspect of the present disclosure is the use of a functionalised polymer, an organic additive, and a precipitant, to remove a target metal species from a solution, wherein the solution comprises the target metal species, a solvent, and optionally non-target metal species that are different from the target metal species. The organic additive is a hydrocarbyl group substituted by at least one heteroatom-containing, and comprises at least one group that binds a metal species. The functionalised polymer is a polymer with at least one covalently bound functional group, and at least one moiety that binds the target metal species. The precipitant comprises at least one hydrophilic moiety and at least one hydrophobic moiety, and at least one group that binds the functionalised polymer and / or the target metal species. Each of the functionalised polymer, organic additive and / or precipitant may be as defined herein for the first aspect of the present disclosure. Discussion herein of the “target metal species” applies equally to the third aspect.

[0019] A fourth aspect of the present disclosure is the use of an organic additive to modify the binding affinity of a metal species in solution for a functionalised polymer, wherein the solution comprises the metal species and a solvent. The organic additive is a hydrocarbyl group substituted by at least one heteroatom-containing, and comprises at least one group that binds a metal species. The functionalised polymer is a polymer with at least one covalently bound functional group, and at least one moiety that binds the metal species. The binding affinity of the metal species for the functionalised polymer is modified relative to without the organic additive. The functionalised polymer and the organic additive are solution phase species. Each of the functionalised polymer, and organic additive may be as defined herein for the first aspect of the present disclosure. The target metal species will be understood by the skilled person to be the metal species for which the binding affinity is modified for the functionalised polymer. Hence, discussion herein of the “target metal species” applies equally to the fourth aspect.

[0020] These aspects and embodiments thereof are set out in the appended independent and dependent claims. It will be appreciated that features of the dependent claims may be combined with each other and with features of the independent claims in combinations other than those explicitly set out in the claims. Furthermore, the approaches described herein are not restricted to specific embodiments such as those set out below, but include and contemplate any combinations of features presented herein. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1: Figure 1 is a key for understanding the remaining figures. Figure 2: Figure 2 is a schematic representation of a functionalised polymer and an organic additive. Figure 3: Figure 3 is a schematic representation of the interaction between the functionalised polymer, the organic additive, the target metal species and the non-target metal species, the target metal species and the non-target metal species both being present in solution. Figure 4: Figure 4 is a schematic representation of the interaction between the functionalised polymer, the organic additive, the target metal species and the non-target metal species, the target metal species and the non-target metal species both being present in solution. Figure 5: Figure 5 is a schematic representation of an aggregate formed between the functionalised polymer, the organic additive, the target metal species, and a precipitant. DETAILED DESCRIPTION

[0021] While various exemplary embodiments are described or suggested herein, other exemplary embodiments utilizing a variety of methods and materials similar or equivalent to those described or suggested herein are encompassed by the general inventive concepts. Those aspects and features of embodiments that are implemented conventionally may not be discussed or described in detail in the interests of brevity. It will thus be appreciated that aspects and features of apparatus and methods described herein which are not described in detail may be implemented in accordance with any conventional techniques for implementing such aspects and features.

[0022] As used in this specification and the claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Unless otherwise stated, the term "about" modifying the quantity of a component refers to variation in the numerical quantity that can occur, for example, through typical measuring and handling procedures used for making concentrates, mixtures or solutions in the real world; through inadvertent error in these procedures; through differences in the manufacture, source, or purity of the materials employed, or to carry out the methods; and the like. The term “about” also encompasses amounts that differ due to different equilibrium conditions for a composition resulting from a particular initial mixture. Whether or not modified by the term "about", the claims include equivalents to the quantities. As used herein, the term “at least” includes the end value of the range that is specified. For example, “at least 50 wt%” includes the value 50 wt%.

[0023] The ranges provided herein provide exemplary amounts of each of the components. Each of these ranges may be taken alone or combined with one or more other component ranges.

[0024] As used herein, wt% means “weight percentage” as the basis for calculating a percentage. Unless otherwise indicated, all wt% values are on an actives basis. Unless otherwise indicated, all % values are calculated on a weight basis, and are provided with reference to the total weight of the product in which the substance is present.

[0025] As used herein, “substantially free” means no more than trace amounts, i.e. the amount of the substance(s) concerned is negligible. In various embodiments, “substantially free” means no more than 1000 ppm, preferably no more than 100 ppm, more preferably no more than 10 ppm, even more preferably no more than 1 ppm of the substance(s) concerned.

[0026] In all aspects of the present disclosure, the disclosure includes, where appropriate, all enantiomers and tautomers of the compounds disclosed herein. A person skilled in the art will recognise compounds that possess optical properties (one or more chiral carbon atoms) or tautomeric characteristics. The corresponding enantiomers and / or tautomers may be isolated / prepared by methods known in the art.

[0027] Some of the compounds disclosed herein may exist as stereoisomers and / or geometric isomers - e.g. they may possess one or more asymmetric and / or geometric centres and so may exist in two or more stereoisomeric and / or geometric forms. The present disclosure contemplates the use of all the individual stereoisomers and geometric isomers of those compounds, and mixtures thereof. The terms used in the claims encompass these forms.

[0028] As used herein, an alkyl group can be a substituted or unsubstituted, linear or branched chain saturated radical. The alkyl group may, for instance be a C1-C35 alkyl group, which is an alkyl group having 1 to 35 carbon atoms, a C1-C30 alkyl group, which is an alkyl group having 1 to 30 carbon atoms, or a C1-C20 alkyl group, which is an alkyl group having 1 to 20 carbon atoms. Examples of alkyl groups having 1 to 20 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, hexadecyl, heptadecyl, octadecyl, nondecyl, eicosyl, and isomeric forms thereof. Cycloalkyl groups are derived from cycloalkanes by removal of a hydrogen atom from a ring carbon atom; they include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, 2-methylcyclopentyl, 2,3-dimethyl-cyclobutyl, 4-methylcyclobutyl, 3-cyclopentylpropyl, and the like.

[0029] As used herein, an alkenyl group can be a substituted or unsubstituted, linear, branched or cyclic unsaturated radical. An alkenyl group thus contains one or more carbon-carbon double bonds and may, for instance, be a C2-C30 alkenyl group. Examples of alkenyl groups having 2 to 20 carbon atoms include ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, dodecenyl, hexadecenyl, heptadecenyl, octadecenyl, nondecenyl, eicosenyl, and isomeric forms thereof. Cycloalkenyl groups include cyclobutenyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, cyclooctenyl, and the like, and isomeric forms thereof.

[0030] As used herein, an aromatic group is a substituted or unsubstituted group derived from arenes by removal of a hydrogen atom from a ring carbon atom. This group includes unsubstituted or substituted heteroaryls. Aryl groups include phenyl, tolyl, xylyl, naphthyl, biphenylyl, and the like, and heteroaryls include pyrrolyl, furanyl, thienyl, oxazolyl, isoxazolyl, thiazolyl, imidazolyl, triazolyl, tetrazolyl, pyridinyl, pyrimidyl, pyrazinyl, pyridazinyl, indolyl, benzofuranyl, benzothiophenyl, thiophenyl, benzimidazolyl, quinolinyl, isoquinolinyl, quinazolinyl, quinoxalinyl, pyrazolyl, and the like.

[0031] When substituted, the above groups may include one or more substituents selected from alkyl, aryl, cyano, amino, alkylamino, arylamino, diarylamino, arylalkylamino, amido, acylamido, hydroxyl, oxo, halo, carboxy, ester, acyl, acyloxy, alkoxy, aryloxy, haloalkyl, sulfonic acid, sulfhydryl (i.e. thiol), alkylthio, arylthio, sulfonyl, phosphoric acid, phosphate ester, phosphonic acid, and phosphonate ester.

[0032] For ease of reference, the features of the present disclosure are now discussed under appropriate section headings. However, the teachings under each section are not limited to the section in which they are found. The skilled person will appreciate that such teachings should be taken in combination as set out in the appended claims and Examples below. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure belongs. Aggregate

[0033] The first aspect of the present disclosure is a product in the form of an aggregate, specifically a “functionalised polymer-organic additive-metal species-precipitant aggregate”. The aggregate may be formed by adding a precipitant as defined herein to a solution phase complex, the complex containing the functionalised polymer-organic additive-metal species as defined herein. The complex is discussed below. The aggregate may therefore be described as a species in which the precipitant molecules are bound to the complex, for example the precipitant may be bound to the functionalised polymer and / or the metal species, the metal species being bound to the functionalised polymer. The metal species may further be bound to the organic additive. The nature of the interactions between these molecules is discussed elsewhere in the specification.

[0034] Generally, in the aggregate, multiple molecules of the precipitant are bound to any one molecule of the functionalised polymer and / or metal species. An aggregate may therefore contain more than one molecule of the functionalised polymer, but each molecule of the functionalised polymer in the aggregate is itself bound to multiple precipitant molecules. Multiple precipitant molecules may also be bound to each metal species. Similarly, multiple molecules of the organic additive may be bound to a metal species.

[0035] Generally, the precipitant molecules that are bound to the functionalised polymer and / or metal species form micelle-type structures, and the surface of each micelle-like structure binds to the functionalised polymer and / or metal species. Typically, hydrophilic groups of the precipitant molecules form the surface of each micelle-like structure and hydrophobic groups of the precipitant molecules form the centre of each micelle-like structure. The functionalised polymer is typically a polyelectrolytic polymer. The hydrophilic surface of each micelle-like structure then binds to the polyelectrolytic polymer, and typically there will be many micelle-like structures bound to one molecule of polymer. The same applies to the interaction of the precipitant with the metal species. The structure of an exemplary aggregate is shown in Figure 5.

[0036] When the aggregate is formed by adding the precipitant to the solution phase complex of the functionalised polymer, organic additive, and target metal species, self-precipitation occurs, such that the precipitates loaded with the target metal species will settle out, can be easily filtered or otherwise separated from the treated solution. In this respect, the product of the present disclosure, may be in the form of a solid or described as a solid species. The separation of the aggregate from the treated solution is discussed further below in the context of the process of the present disclosure. Functionalised polymer

[0037] By the term “functionalised polymer” is meant a reaction product of a polymer backbone and at least one functional group, the polymer backbone being a molecule composed of multiple repeating units. Where the specification refers to “polymer”, it is meant “functionalised polymer”. An unfunctionalised polymer is referred to herein as “polymer backbone”. As the skilled person will appreciate, the covalently bound functional group is independent of the repeating units forming the polymer. For example, polyethyleneimine is a polymer with repeating units composed of the amine group and two carbon aliphatic CH2CH2 spacers, the amine group is not a “covalently bound functional group” within the meaning of the present invention, it is part of the polymer backbone or “unfunctionalised” polymer.

[0038] The person skilled in the art using routine polymer synthesis methods such as routine coupling chemistry is able to prepare the functionalised polymer. The functional group(s) are covalently attached to the polymer backbone, and attachment of such groups (either directly or via a protected version which is deprotected at a later point in time) can be carried out after polymerisation. Deprotection may be performed if necessary to provide the functionalised polymer. The skilled person will be familiar with suitable protection and deprotection mechanisms.

[0039] The functionalised polymer described in the present disclosure is designed with at least one functional group covalently bound to the polymer backbone. Such functional group incorporates elements such as carbon, oxygen, nitrogen, phosphorus, and sulphur. This polymer design significantly enhances the recovery of and selectivity towards metal species since it enables the product and process of the present disclosure to be configured for interaction(s) with a target metal species. The functionalisation of the polymer backbone can be controlled or selected so as to ‘fine-tune’ the polymer’s affinity for one or more target metal species.

[0040] The ability to adjust the functionalization enables the recovery process to be designed and optimized based on the specific nature, e.g. type, of target metal species in a mixture of metal species. In some embodiments, the functionalization enables the recovery process to be designed and optimized for the recovery of one or more target d-block metal species in a metal species mixture, the mixture including non-target metal species (e.g. non-target d-block or other metal species). In these embodiments, the functionalisation may increase the % recovery of the target metal species compared to the unfunctionalised polymer. In this respect, the backbone of the functionalised polymer is not limited. It is the covalently bound functional group that plays a central role in the selective recovery of the target metal species. Hence, the polymer backbone may be any polymer that is suitable for functionalisation with one or more covalently bound groups as defined herein. Polymer backbone

[0041] As noted above, the polymer backbone is a molecule comprised of multiple repeating units. In some embodiments the backbone of the functionalised polymer is a polyelectrolytic polymer when in aqueous solution. The polymer backbone may therefore be an anionic polymer when in aqueous solution, a cationic polymer when in aqueous solution, or an ampholytic polymer when in aqueous solution. The term “aqueous” is used herein to refer to a solution containing at least 50 wt% water, based on the total weight of the solution. The term “ampholytic polymer” as used herein, refers to a polyelectrolyte comprising macromolecules containing both cationic and anionic groups. An ampholytic polymer in which ionic groups of opposite charge are incorporated into the same pendant groups may be called, depending on the structure of the pending groups, a zwitterionic polymer, polymeric inner salt, or polybetaine.

[0042] Anionic, cationic and amphoteric polymer backbones are commercially available or readily synthesised using polymer synthesis methods available in the art. When obtained from a commercial source, the polymer backbone may be supplied neat or in a solvent. Poly(ethyleneimine), for example, is available from Sigma Aldrich as a viscous liquid containing less than 1.0 wt% water (i.e. neat) or as an aqueous solution (containing 50 wt% or more of water). When the polymer backbone is supplied neat, it may be dissolved in one or more solvents prior to its functionalisation. Suitable solvents are known to a person skilled in the art and are discussed herein. In preferred embodiments, the polymer backbone is dissolved in an aqueous solvent prior to functionalisation and subsequent use. When the polymer backbone is supplied or provided in a solvent, said solvent is preferably aqueous.

[0043] In some embodiments the polymer backbone is an organic polymer with N-containing groups, including e.g. amines, imines, amides, imides, oximes, enamines, nitriles, hydrazines, hydrazides, carbazides, hydrazones, carboazones, N-heterocycles, and the like. Suitable N-heterocycles are aliphatic or aromatic N-heterocycles. For example, aziridine, azolidine, piperidine, azepane, pyrrole, imidazole, thiazole, or pyridine. The amine groups may be primary, secondary, tertiary or a combination thereof. Such polymer backbones are examples of those which are cationic when in aqueous solution.

[0044] In some embodiments, the polymer backbone of the functionalised polymer is an organic polymer with amine, imine, amide, or N-heterocycle groups, preferably amine, imine or amide groups. Suitable N-heterocycles are listed in the preceding paragraph. The amine groups may be primary, secondary, tertiary or a combination thereof. In some embodiments the polymer backbone of the functionalised polymer is a polymer derived from aziridine, i.e. containing aliphatic hydrocarbon chains and amine groups.

[0045] Where the polymer backbones include aliphatic hydrocarbon chains, they may be cyclic or acyclic, linear or branched, preferably the hydrocarbon chains are acyclic, particularly preferred are branched acyclic hydrocarbon chains. Poly(ethyleneimine) or PEI is otherwise known in the art as a polyaziridine, it is an example of a polymer backbone derived from aziridine. Branched PEIs can, for example, be synthesized by the ring opening polymerization of aziridine. Depending on the reaction conditions, different degrees of branching can be achieved. The nature or the degree of branching is not limited in the present disclosure.

[0046] In some embodiments, the polymer backbone of the functionalised polymer is a polyamine, a polyamide, or a combination thereof. The amine groups may be primary, secondary, tertiary or a combination thereof. Examples include, but are not limited to, poly(ethyleneimine), polyvinylamine, polyallylamine, chitosan, polylysine, polyarginine, polyamide, polyacrylamide, or a combination thereof.

[0047] In preferred embodiments, the polymer backbone is selected from a polymer derived from aziridine (e.g. polyethyleneimine), polyvinylamine, polyallylamine, chitosan, polylysine, polyarginine, or a combination thereof.

[0048] In some embodiments, the polymer backbone is an organic polymer with O-containing groups, P-containing groups, and / or S-containing groups, including e.g. carboxyl groups, sulfonic acid groups, phosphoric acid groups, phosphinic acid groups, phosphonic acid groups, and the like. Such polymer backbones are examples of those which are anionic when in aqueous solution. Where these polymer backbones include aliphatic hydrocarbon chains, they may be cyclic or acyclic, linear or branched, preferably the hydrocarbon chains are acyclic.

[0049] In some embodiments, the polymer backbone of the functionalised polymer is an organic polymer with carboxyl, or sulfonic acid groups. In preferred embodiments the polymer backbone of the functionalised polymer is a carboxylate, sulfate, or sulfonate polymer. Examples of polymer backbones with carboxyl groups include, but are not limited to, aliphatic hydrocarbons (e.g. a polyolefin) substituted with carboxyl groups, polyesters substituted with carboxyl groups, polyamides substituted with carboxyl groups, and polysulfides with carboxyl groups. Examples of polymer backbones with sulfonic acid groups include, but are not limited to, polyolefins substituted with sulfonate or sulfate groups, polyesters substituted with sulfonate or sulfate groups, polysulfides substituted with sulfonate or sulfate groups, and poly(sodium styrene sulfonate).

[0050] In some embodiments, the polymer backbone of the functionalised polymer comprises poly(meth)acrylate, polymaleate, polyaspartic acid, polyglutamic acid, alginic acid, polysulfonate, polyphosphoric acid, or a combination thereof. In preferred embodiments, the polymer backbone of the functionalised polymer comprises poly (meth)acrylate, polymaleate, polysulfonate, or a combination thereof.

[0051] The polymer backbone may have a weight average molecular weight, as measured by Gel Permeation Chromatography (GPC) with a suitable calibration standard (e.g. polystyrene), of from about 100 Da to about 1000 kDa. For example, the polymer backbone may comprise an organic polymer with N-containing groups selected from amines, imines and N-heterocycles, preferably amine groups, and have a weight average molecular weight as measured by GPC and calibration of from about 100 Da to about 1000 kDa. In the mirror system, i.e. a polymer backbone forming an anionic polymer in aqueous solution, the polymer backbone may comprise an organic polymer with carboxyl, sulfonic acid, phosphonic acid, phosphoric acid and / or phosphinic acid groups, preferably carboxyl and / or sulfonic acid groups, and have a weight average molecular weight as measured by GPC and calibration of from about 100 Da to about 1000 kDa. Functional Group

[0052] The functional group is introduced onto the polymer backbone (molecule composed of multiple repeating units) by any suitable method as discussed above; said functional group incorporating elements such as carbon, oxygen, nitrogen, phosphorus, and sulphur. Hence the functionalised polymer may be described as a reaction product of a polyelectrolytic polymer and an organic moiety with sulphur, nitrogen, phosphorus, oxygen, and / or carbon functionality.

[0053] The functionalised polymer further comprises at least one moiety that binds a metal species, specifically the target metal species. In some embodiments one or more of the covalently bound functional groups of the polymer is a moiety that binds the target metal species. In some embodiments the functionalised polymer comprises a second moiety that binds the target metal species. Said moiety may be present in the polymer backbone.

[0054] The at least one moiety or group that binds the target metal species comprises a heteroatom. The heteroatom may otherwise be referred to as a “donor atom” and is selected from sulfur, phosphorus, nitrogen, and oxygen. Consequently, the at least one group on the functionalised polymer that binds the target metal species comprises at least one sulfur atom, phosphorus atom, nitrogen atom, oxygen atom, or a combination thereof. In preferred embodiments the at least one group on the functionalised polymer that binds the target metal species comprises at least one nitrogen atom, sulphur atom, oxygen atom, or a combination thereof. Suitable N-containing groups, S-containing groups, P-containing groups and O-containing groups are defined above for the polymer backbone and are not repeated here for conciseness. Specifically, the N-containing groups are defined in the context of cationic polymer backbones, and the S-containing groups, P-containing groups, and O-containing groups are defined in the context of anionic polymer backbones. Hence, these groups may be present as part of the polymer backbone, and / or may be introduced by the covalently bound functional group.

[0055] As a non-limiting example, the polymer backbone may be a polymer derived from aziridine, such as poly(ethyleneimine), and the functional group may be an aliphatic or aromatic hydrocarbon having 3 to 12 carbon atoms. The polymer backbone in this non-limiting example includes one or more heteroatom, namely N atoms, that are suitable for binding a metal species, and the functionalisation of said N atoms is believed to increase the binding affinity of the metal species for the polymer. Without wishing to be bound by theory, the inventors believe that the increase in binding affinity is due to electronic and steric considerations of the functionalised polymer and target metal species in solution. Hence the functionalised polymer in this nonlimiting example has covalently bound functional groups, namely the aliphatic or aromatic hydrocarbon having 3 to 12 carbon atoms, and at least one moiety that binds the target metal species, namely the functionalised N atoms in the polymer backbone. The functionalised polymer in this non-limiting example is a reaction product of the polymer derived from aziridine and an aliphatic or aromatic hydrocarbon having 3 to 12 carbon atoms.

[0056] A mirror system, e.g. where the polymer backbone is an anionic polymer in aqueous solution is also envisaged. In the mirror system, the functional group may be an aliphatic or aromatic hydrocarbon having 3 to 12 carbon atoms as defined herein. The polymer backbone still includes one or more heteroatom, namely O and / or S atoms, (e.g. poly(meth)acrylate, polymaleate, polysulfonate) that are suitable for binding a metal species, and the functionalisation of said polymer backbone is believed to increase the binding affinity of the target metal species for the functionalised polymer.

[0057] An example interaction between a polymer backbone and functional group is shown in Figure 2. An example interaction between a functionalised polymer and target metal species is then shown in Figures 3 and 4.

[0058] The functionalised polymer is bound to the target metal species electrostatically or coordinatively. In preferred embodiments the functionalised polymer is electrostatically bound with the metal species, i.e. a non-covalent interaction. The nature of the electrostatic or non-covalent association between the functionalised polymer and metal species is not limited; it may be dipole-dipole interactions, London dispersion forces, hydrogen bonding, ionic bonding, or a combination thereof. The solid line in Figures 3 and 4 is therefore schematic, it does not necessarily represent a covalent bond.

[0059] In some embodiments the functionalised polymer comprises at least one moiety that binds the organic additive. In some embodiments one or more of the covalently bound functional groups of the polymer binds the organic additive. In some embodiments the functionalised polymer comprises a second moiety that binds the organic additive, such moiety may also be different from the moiety that binds the target metal species.

[0060] An example interaction between the functionalised polymer and the organic additive is shown in Figure 2. An example interaction between the functionalised polymer, organic additive and target metal species is shown in Figure 3. In Figure 3 the functionalised polymer is bound to the organic additive, and organic additive is bound to the target metal species. In other embodiments the functionalised polymer may be bound to the target metal species, and the organic additive may be bound to the functionalised polymer and / or the target metal species.

[0061] The functionalised polymer may be electrostatically or coordinatively bound to the organic additive. In preferred embodiments the functionalised polymer is electrostatically bound with the organic additive, i.e. a non-covalent interaction. The organic additive is not a functional group of the polymer. The nature of the electrostatic or non-covalent association between the functionalised polymer and organic additive is not limited; it may be dipole-dipole interactions, London dispersion forces, hydrogen bonding, ionic bonding, or a combination thereof. The solid line in Figure 3 is therefore schematic, it does not necessarily represent a covalent bond.

[0062] As a continuation of the above non-limiting example with an aliphatic or aromatic hydrocarbon having 3 to 12 carbon atoms as the functional group, the functionalised N atoms in the polyaziridine backbone or functionalised O or S atoms in the mirror system may, for instance, bind the organic additive. Being positively charged in solution, the functionalised heteroatoms may interact electrostatically with the organic additive. The nature of the electrostatic interaction is not limited. A mirror system, i.e. where the functionalised polymer is negatively charged, is also envisaged.

[0063] Alternatively, the organic additive may be chosen so that it binds a non-target metal species in solution, leaving the functionalised polymer to bind the target metal species as outlined above.

[0064] In view of the multiple molecules of target metal species binding to the functionalised polymer and the possible interaction of the organic additive with the functionalised polymer, the polymer backbone may have a plurality of covalently bound functional groups. Said plurality of covalently bound functional groups may be the same or different. They may, for instance, be selected in order to bind preferentially with the organic additive or the target metal species. The present disclosure is not limited in this respect and the skilled person, understanding the principles underlying the present disclosure, will be able to functionalise the polymer backbone depending on the target metal species and / or organic additive employed.

[0065] The polymer may be a homopolymer, copolymer or an interpolymer. As used herein, the term “interpolymer” refers to a complex comprising at least two polymers. In such interpolymers, one or more of the constituent polymers may be a homopolymer or a copolymer. Without wishing to be bound by theory, it is believed that the complex between the at least two polymers in an interpolymer arises due to non-covalent interactions. Aliphatic or Aromatic Hydrocarbon

[0066] In some embodiments the covalently bound functional group of the polymer comprise an aliphatic or aromatic hydrocarbon. By the term “aliphatic” as used herein is meant an acyclic or cyclic, saturated or unsaturated carbon compound, which is not aromatic. The term “aromatic” is defined hereinabove. The aliphatic or aromatic hydrocarbon may have 3 to 20 carbon atoms. In preferred embodiments, the aliphatic or aromatic hydrocarbon may have 3 to 12 carbon atoms.

[0067] The aliphatic hydrocarbon may be an alkyl or alkenyl group as defined herein, having 3 to 20 carbon atoms, preferably having 3 to 12 carbon atoms. Examples for the alkyl group include propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, and isomeric forms thereof, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, 2- methylcyclopentyl, 2,3-dimethyl-cyclobutyl, 4-methylcyclobutyl, and 3-cyclopentylpropyl. Examples for the alkenyl group include propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, dodecenyl, hexadecenyl, heptadecenyl, octadecenyl, nondecenyl, eicosenyl, and isomeric forms thereof. Cycloalkenyl groups include cyclobutenyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, cyclooctenyl, and the like, and isomeric forms thereof. In preferred embodiments the aliphatic hydrocarbon is an alkyl group having 3 to 20 carbon atoms, particularly preferred are alkyl groups having 3 to 12 carbon atoms.

[0068] It may be beneficial to functionalise a polymer backbone which is a polyamine, a polyamide, or a combination thereof with one or more aliphatic hydrocarbon groups; such embodiments have been shown to enhance the recovery of platinum group species, including rhodium and palladium cations, from a mixture of metal species (e.g. platinum group species and other d-block metal species such as nickel species), compared to the unfunctionalised polymer, i.e. the polyamine, polyamide or combination thereof without the aliphatic hydrocarbon functionalisation. Examples of a polymer backbone which is a polyamine, a polyamide, or a combination thereof are described above. The amine groups may be primary, secondary, tertiary or a combination thereof. Examples include, but are not limited to, poly(ethyleneimine), polyvinylamine, polyallylamine, chitosan, polylysine, polyarginine, polyamide, polyacrylamide, or a combination thereof. As well as enhancing %recovery, the functionalisation of the polymer backbone which is a polyamine, a polyamide, or a combination thereof, improved selectivity of the recovery for the target metal species, e.g. the platinum group species over the non-target metal species, e.g. including nickel, iron and / or aluminium.

[0069] The functionalisation with aliphatic hydrocarbon group(s) has also been shown to be beneficial for the selective recovery of target metal species with a variety of organic additives as defined herein, including organic additives with N-containing groups, S-containing groups, O-containing groups, and combinations thereof. Particular benefits in terms of effective and selective metal recovery of platinum group species were observed with organic additives including S-containing groups, such as organic additives including a combination of S-containing groups and O-containing groups, or S-containing groups and N-containing groups. The skilled person will understand that this combination of functionality may be achieved by using an organic additive containing multiple heteroatoms such as a thioamide, thiocarboxylic acid, or sulfonic acid, and / or by combining organic additives with different heteroatoms such as a N-heterocycle and a sulfonic acid or carboxylic acid and a thiol group. Such benefits are supported by the Examples described below in which thiourea is employed as an example thioamide, TGA is employed as an example of a carboxylic acid and a thiol group, and 2-aminopyridine is employed as an example N-heterocycle either alone or in combination with another organic additive described herein.

[0070] It may, for example, be beneficial to use an organic additive for its ability to enhance recovery of metal species, and combine this additive with one or more other organic additives to introduce or enhance selectivity for a target metal species. The use of more than one organic additive in any of the embodiments described herein may result in synergy, i.e. the combination of additives may have an effect which is greater than the sum of their individual effect on the binding affinity of the target metal species for the functionalised polymer.

[0071] The aromatic hydrocarbon may be an aryl or alkaryl, where aryl and alkyl are as defined herein, having 3 to 20 carbon atoms, preferably having 3 to 12 carbon atoms. Aryl groups include phenyl, tolyl, xylyl, naphthyl, and biphenyl. Examples for the alkyl group include methyl, ethyl, propyl, butyl, pentyl, hexyl, and isomeric forms thereof. In some embodiments the aromatic hydrocarbon is an aryl or alkaryl group having 3 to 12 carbon atoms. In preferred embodiments the aromatic hydrocarbon is selected from phenyl, tolyl, xylyl, Ci-6-phenyl, C1-6-tolyl, and Ci-6-xylyl. In particularly preferred embodiments, the aromatic hydrocarbon is selected from Ci-6-phenyl, Ci-6-tolyl, and Ci-6-xylyl.

[0072] It may be beneficial to functionalise a polymer backbone which is a polyamine, a polyamide, or a combination thereof with one or more aromatic hydrocarbon groups, especially where the aromatic hydrocarbon is an alkaryl as defined above. Examples of a polymer backbone which is a polyamine, a polyamide, or a combination thereof are described above. The amine groups may be primary, secondary, tertiary or a combination thereof. Examples include, but are not limited to, poly(ethyleneimine), polyvinylamine, polyallylamine, chitosan, polylysine, polyarginine, polyamide, polyacrylamide, or a combination thereof. As well as enhancing %recovery, the functionalisation of the polymer backbone which is a polyamine, a polyamide, or a combination thereof, with an alkaryl as defined above improved selectivity of the recovery for the target metal species over the non-target metal species.

[0073] The functionalisation with aromatic hydrocarbon group(s) has also been shown to be beneficial for the recovery of target metal species with a variety of organic additives as defined herein, including organic additives with N-containing groups, S-containing groups, O-containing groups, and combinations thereof. As noted above, the skilled person will understand that this combination of functionality may be achieved by using a multi-functional organic additive (e.g. picolinic acid or an isomer thereof) and / or by combining organic additives such as a N-heterocycle and a compound with a carboxylic acid group and an amino group.

[0074] As noted above, the at least one moiety or group of the functionalised polymer that binds the target metal species comprises a heteroatom. Hence, when the covalently bonded functional group comprises an aliphatic or aromatic hydrocarbon as defined above, the functionalised polymer includes a different group or moiety to bind the target metal species. Said moiety may be present in the polymer backbone or a further functional group introduced onto the polymer backbone. If a further functional group is employed, it may be a heteroatom-containing functional group as defined below. In some embodiments the functionalised polymer may therefore comprise an aliphatic or aromatic hydrocarbon and at least one covalently bound functional group which comprises at least one heteroatom selected from N, O, P, S, and combinations thereof. Preferably at least one heteroatom selected from N, 0, S, and combinations thereof.

[0075] In some embodiments the at least one moiety that binds the target metal species is present in the polymer backbone. The at least one moiety that binds the target metal species comprises at least one heteroatom selected from N, 0, P, S, and combinations thereof. Preferably at least one heteroatom selected from N, 0, S, and combinations thereof.

[0076] In some embodiments the functionalised polymer may interact with the organic additive. The functionalised polymer may, for example, be bound to the organic additive. The nature of the binding it not limited; it may be electrostatic or coordinative. Preferably the functionalised polymer is electrostatically bound to the organic additive when the at least one covalently bound functional group of the polymer is an aliphatic or aromatic hydrocarbon as defined above, e.g. a dipole-dipole interaction, London dispersion forces, hydrogen bonding, ionic bonding, or a combination thereof. The aliphatic or aromatic hydrocarbon may, for example, result in a positive charge on the polymer backbone, and said positive charge may result in electrostatic bonding between the functionalised polymer and organic additive and / or metal species.

[0077] In some embodiments the polymer backbone of the functionalised polymer is a polyamine, a polyamide, or a combination thereof, and the at least one covalently bound functional group comprises an aliphatic or aromatic hydrocarbon having 3 to 20 carbon atoms. In preferred embodiments the aliphatic or aromatic hydrocarbon is an alkyl, alkenyl or alkaryl group having 3 to 20 carbon atoms. In particularly preferred embodiments, the aliphatic or aromatic hydrocarbon is selected from propyl, butyl, pentyl, hexyl, heptyl, octyl nonyl, decyl, undecyl, dodecyl, and isomeric forms thereof, Ci-6-phenyl, Ci-6-tolyl, and Ci-6-xylyl.

[0078] In some embodiments, the polymer backbone of the functionalised polymer is selected from a polymer derived from aziridine (e.g. polyethyleneimine), polyvinylamine, polyallylamine, chitosan, polylysine, polyarginine, or a combination thereof, and the at least one covalently bound functional group comprises an aliphatic or aromatic hydrocarbon having 3 to 20 carbon atoms. In preferred embodiments the aliphatic or aromatic hydrocarbon is an alkyl, alkenyl or alkaryl group having 3 to 20 carbon atoms. In particularly preferred embodiments, the aliphatic or aromatic hydrocarbon is selected from propyl, butyl, pentyl, hexyl, heptyl, octyl nonyl, decyl, undecyl, dodecyl, and isomeric forms thereof, Ci-6-phenyl, Ci-6-tolyl, and Ci-6-xylyl.

[0079] In some embodiments, the polymer backbone of the functionalised polymer is selected poly(meth)acrylate, polymaleate, polyaspartic acid, polyglutamic acid, alginic acid, polysulfonate, polyphosphoric acid, or a combination thereof, and the at least one covalently bound functional group comprises an aliphatic or aromatic hydrocarbon having 3 to 20 carbon atoms. In preferred embodiments the aliphatic or aromatic hydrocarbon is an alkyl, alkenyl or alkaryl group having 3 to 20 carbon atoms. In particularly preferred embodiments, the aliphatic or aromatic hydrocarbon is selected from propyl, butyl, pentyl, hexyl, heptyl, octyl nonyl, decyl, undecyl, dodecyl, and isomeric forms thereof, Ci-6-phenyl, Ci-6-tolyl, and Ci-6-xylyl. Heteroatom-containing Functional groups

[0080] In some embodiments the covalently bound functional group comprises at least one heteroatom. The heteroatom may be selected from N, O, P, S and combinations thereof. In preferred embodiments the heteroatom is selected from N, O, S, and combinations thereof. In particularly preferred embodiments, the heteroatom is selected from N, S, and combinations thereof, or N, O, and combinations thereof. A functional group comprising a heteroatom selected from N, O, S, P, and combinations thereof, is also described herein as a N-containing group, 0-containing group, S-containing group, P-containing group, or a combination thereof.

[0081] When the functional group on the polymer backbone includes a heteroatom-containing group to bind the target metal species, said group may include one or more heteroatoms known in the art to interact favourably with and bind to the metal in the target metal species (e.g. N and / or O). In such embodiments, the organic additive may be configured to include one or more heteroatoms known in the art to bind the non-target metal species and / or the target metal species (e.g. N, 0 and / or S). Additionally or alternatively, the functional group may be chosen such that the one or more heteroatoms therein are the same as those in the polymer backbone (e.g. N or 0), and the organic additive may be chosen with heteroatom(s) known to bind the metal in the target metal species (e.g. S for platinum group species). The organic additive may therefore include one or more heteroatoms which is different from the heteroatom(s) in the functionalised polymer. For example, the functionalised polymer may comprise one or more N atoms, and the organic additive may comprise S and / or 0 atoms, or vice versa for the mirror system.

[0082] Suitable heteroatom-containing groups are known in the art and include, but are not limited to, the following O-containing, S-containing, N-containing and P-containing groups.

[0083] O-containing groups: OH, ethers, carboxyls, carbonyls, sulfonic acids, sulfinic acids, thioketones, thials, thioesters, oximes, hydrazides, carbazides, furanyls, oxazolyls, isoxazolyls, benzofuranyls, quinoxalinyls, phosphoric acids, phosphinic acids, phosphonic acids; preferably OH, carboxyls, carbonyls;

[0084] S-containing groups: sulfonic acids, sulfinic acids, sulfhydryls, sulfides, thioketones, thials, thioesters, thioamides, thienyls, thiazolyls, benzothiophenyls, thiophenyls; preferably sulfonic acids, sulfinic acids, sulfhydryls, thioketones, thials, thioesters, athioamides;

[0085] P-containing groups: phosphoric acids, phosphinic acids, phosphonic acids; and

[0086] N-containing groups: thioamides, cyano groups, amino groups, imino groups, imides, amides, amidines, oximes, hydrazides, carbazides, quaternary nitrogen groups, pyrrolyls, oxazolyls, isoxazolyls, thiazolyls, imidazolyls, triazolyls, tetrazolyls, pyridinyls, pyrimidyls, pyrazinyls, pyridazinyls, indolyls, benzimidazolyls, quinolinyls, isoquinolinyls, quinazolinyls, quinoxalinyls, and pyrazolyls; preferably thioamides, amino groups, amides, quaternary nitrogen groups, pyrrolyls, triazolyls, tetrazolyls, pyridinyls, pyrimidyls, pyrazinyls, pyridazinyls.

[0087] In some embodiments the at least one covalently bound functional group of the polymer comprises one or more hydroxyl groups, ether groups, carboxyl groups, carbonyl groups, sulfonic acid groups, sulfinic acid groups, sulfhydryl groups, sulfide groups, thioketone groups, thial groups, thioester groups, thioamide groups, phosphoric acid groups, phosphinic acid groups, phosphonic acid groups, cyano groups, amino groups, imino groups, imide groups, amide groups, amidine groups, oxime groups, hydrazide groups, carbazide groups, quaternary nitrogen groups, N-heterocycles, or a combination thereof. Suitable N-heterocycles include pyrrolyls, imidazolyls, triazolyls, tetrazolyls, pyridinyls, pyrimidyls, pyrazinyls, pyridazinyls, indolyls, benzimidazolyls, quinolinyls, isoquinolinyls, quinazolinyls, quinoxalinyls, and pyrazolyls.

[0088] In some embodiments the at least one covalently bound functional group of the polymer comprises one or more hydroxyl groups, ether groups, carboxyl groups, carbonyl groups, sulfonic acid groups, sulfinic acid groups, sulfhydryl groups, sulfide groups, thioketone groups, thial groups, thioester groups, thioamide groups, cyano groups, amino groups, imino groups, imide groups, amide groups, amidine groups, oxime groups, hydrazide groups, carbazide groups, quaternary nitrogen groups, N-heterocycles, or a combination thereof. Suitable N-heterocycles include pyrrolyls, imidazolyls, triazolyls, tetrazolyls, pyridinyls, pyrimidyls, pyrazinyls, pyridazinyls, indolyls, benzimidazolyls, quinolinyls, isoquinolinyls, quinazolinyls, quinoxalinyls, and pyrazolyls.

[0089] In some embodiments the at least one covalently bound functional group of the polymer comprises one or more sulfonic acid groups, sulfinic acid groups, sulfhydryl groups, sulfide groups, thioketone groups, thial groups, thioester groups, thioamide groups, cyano groups, amino groups, imino groups, imide groups, amide groups, amidine groups, oxime groups, hydrazide groups, carbazide groups, quaternary nitrogen groups, N-heterocycles, or a combination thereof, or one or more hydroxyl groups, ether groups, carboxyl groups, carbonyl groups, cyano groups, amino groups, imino groups, imide groups, amide groups, amidine groups, oxime groups, hydrazide groups, carbazide groups, N-heterocycles, or a combination thereof.

[0090] In some embodiments the at least one covalently bound functional group of the polymer comprises one or more sulfonic acid groups, sulfinic acid groups, sulfhydryl groups, sulfide groups, thioamide groups, amino groups, imino groups, imide groups, amide groups, amidine groups, oxime groups, hydrazide groups, carbazide groups, quaternary nitrogen groups, N-heterocycles, or a combination thereof, or one or more hydroxyl groups, carboxyl groups, carbonyl groups, amino groups, imino groups, imide groups, amide groups, amidine groups, oxime groups, hydrazide groups, carbazide groups, quaternary nitrogen groups, N-heterocycles, or a combination thereof.

[0091] When the covalently bound functional group comprises a quaternary nitrogen, the quaternary nitrogen typically has the formula: (NR1R2R3)+, wherein R1, R2, and R3 are independently selected from a substituted or unsubstituted alkyl group or a substituted or unsubstituted alkenyl group. In some embodiments R1, R2, and R3 are independently selected from a substituted or unsubstituted C1-18 alkyl group or a substituted or unsubstituted C1-18 alkenyl group. In some embodiments R1, R2, and R3 are independently selected from a substituted or unsubstituted C1-12 alkyl group or a substituted or unsubstituted C1-12 alkenyl group. In some embodiments R1, R2, and R3 are independently selected from a substituted or unsubstituted C1-6 alkyl group or a substituted or unsubstituted C1-6 alkenyl group. The quaternary nitrogen group may comprise an anion, for instance a halide such as a fluoride, chloride, bromide or iodide anion, a hydroxyl or a sulfate. An example of a quaternary nitrogen group is -(NMe3)+CI'.

[0092] In some embodiments, the covalently bound functional group of the polymer may comprise an aliphatic hydrocarbon substituted by at least one S-containing group, N- containing group, and / or O-containing group, said group as defined above. For example, in some embodiments the functionalised polymer is a reaction product of the polymer backbone defined above and one or more of an aliphatic carboxylic acid, an epoxide, an episulfide, polyethylene glycol, polyvinyl alcohol, or polyamide. Hence, the above-defined hydroxyl, carboxyl, sulfhydryl, ether, amino, or amide groups, may be derived from such a reaction. Suitable reactions are known in the art and the skilled person would be readily able to identify a polymer backbone that would react with one or more of an aliphatic carboxylic acid, an epoxide, an episulfide, polyethylene glycol, polyvinyl alcohol, or polyamide. The aliphatic carboxylic acid may be an alkyl or alkenyl carboxylic acid, the alkyl and alkenyl groups being defined as above for the quaternary nitrogen functional group. The epoxide and episulfide may be an aliphatic epoxide or aliphatic episulfide, the aliphatic group being an alkyl group or an alkenyl group as defined above for the quaternary nitrogen functional group.

[0093] In some embodiments the functionalised polymer is a reaction product of a polyamine, a polyamide, or a combination thereof, and one or more of an aliphatic carboxylic acid, an epoxide, an episulfide, polyethylene glycol, polyvinyl alcohol, or polyamide. Formula (III)

[0094] In some embodiments the at least one covalently bound functional group of the polymer is represented by formula (III): wherein R3 and R4 are independently selected from -H, =0, -SRa, -ORa, =S, =N, -N(Ra)2, -N(Rb)3+A_, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -N(Rb)2, -N(Rb)3+A-, -C(O)Rb, -C(O)YRb, -(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SC(O) NRbRb, -OC(S)NRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, or a combination thereof; wherein X5 is -ORb, -SRb, -N(Rb)2, -N(Rb)3+A-, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, C(NRb)YRb, -C(NRb)NRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SC(O) NRbRb, OC(S)NRbRb, -SxC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, ora combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is O or S; wherein A is an anion; wherein x is an integer from 1 to 4; wherein n is 0 or an integer from 1 to 8; and wherein m is 0 or an integer from 1 to 8.

[0095] In some embodiments, Xe is -N(Rb)2, -N(Rb)3+A’, -C(O)NRbRb,-C(O)NRaNRbRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)2NRaNRbRb, -SC(O)NRbRb, -OC(S)NRbRb, -SxC(O)NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, or a combination thereof, wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Y is O or S; wherein A is an anion; and wherein x is an integer from 1 to 4. In some embodiments, Xe is -N(Rb)2, -N(Rb)3+A_, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, or a combination thereof, wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Y is O or S; and wherein A is an anion. In some embodiments, Xe is -N(Rb)2, -N(Rb)3+A_, -C(NRc)Rb, -C(NRb)NRbRb, or a combination thereof, wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; and wherein A is an anion. In any of these embodiments, A is selected from halide (e.g. fluorine, chlorine, bromine and iodine), hydroxyl and sulfate anions. Preferably A is selected from chlorine or bromine.

[0096] In other embodiments, Xe is -ORb, -SRb, -C(O)Rb, -C(O)YRb, -C(S)Rb, -C(S)YRb, -S(O)ORb, -S(O)2ORb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6alkenyl.

[0097] In any of the above embodiments, Ra and Rb are independently selected from H and Ci-6 alkyl.

[0098] In some embodiments, n is 0 and m is an integer from 1 to 8. In some embodiments, n is 0 and m is an integer from 1 to 6. In some embodiments, n is 0 and m is an integer from 1 to 4. In some embodiments, n is an integer from 1 to 8 and m is 0. In some embodiments, n is an integer from 1 to 6 and m is 0. In some embodiments, n is an integer from 1 to 4 and m is 0. In such embodiments where either n or m is equal to zero, it is preferred that R3 or R4 (whichever is present) is -H or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -N(Rb)2, -N(Rb)3+A-, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SC(O)NRbRb, -OC(S)NRbRb, -SxC(O)NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, ora combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Y is O or S; and wherein x is an integer from 1 to 4. In particularly preferred embodiments where n or m is equal to zero, R3 or R4 (whichever is present) is -H or a C1-6 alkyl or C1-6 alkenyl.

[0099] In some embodiments, n is an integer from 1 to 8 and m is an integer from 1 to 8. In some embodiments, n is an integer from 1 to 6, and m is an integer from 1 to 6. In some embodiments, n is an integer from 1 to 4, and m is an integer from 1 to 4.

[0100] In some embodiments, Xe is -N(Rb)2, -N(Rb)3+A', -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, or a combination thereof, wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Y is O or S; wherein A is an anion; n is 0 and m is an integer from 1 to 4, or n is an integer from 1 to 4 and m is 0. In some embodiments, Xe is -N(Rb)2, -N(Rb)3+A', -C(NRc)Rb, -C(NRb)NRbRb, or a combination thereof, wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein A is an anion; n is 0 and m is an integer from 1 to 4, or n is an integer from 1 to 4 and m is 0. In any of these embodiments, A is selected from halide (fluorine, chlorine, bromine and iodine), hydroxyl and sulfate anions. Preferably A is selected from chlorine or bromine.

[0101] In other embodiments, Xe is -ORb, -SRb, -C(O)Rb, -C(O)YRb, -C(S)Rb, -C(S)YRb, -S(O)ORb, -S(O)2ORb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; n is 0 and m is an integer from 1 to 4, or n is an integer from 1 to 4 and m is 0.

[0102] In preferred embodiments where either n or m is equal to zero, R3 or R4 (whichever is present) is as defined above. In particularly preferred embodiments where n or m is equal to zero, R3 or R4 (whichever is present) is -H or a C1-6 alkyl or C1-6 alkenyl.

[0103] In some embodiments, X6 is -N(Rb)2, -N(Rb)3+A; -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, or a combination thereof, wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Y is O or S; wherein A is an anion; n is an integer from 1 to 4 and m is an integer from 1 to 4. In some embodiments, Xe is -N(Rb)2, -N(Rb)3+A', -C(NRc)Rb, -C(NRb)NRbRb, or a combination thereof, wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein A is an anion; n is an integer from 1 to 4 and m is an integer from 1 to 4. In any of these embodiments, A is selected from halide (fluorine, chlorine, bromine and iodine), hydroxyl and sulfate anions. Preferably A is selected from chlorine or bromine.

[0104] In other embodiments, X6 is -ORb, -SRb, -C(O)Rb, -C(O)YRb, -C(S)Rb, -C(S)YRb, -S(O)ORb, -S(O)2ORb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; n is an integer from 1 to 4 and m is an integer from 1 to 4.

[0105] In some embodiments, R3 is selected from -H, =N, -N(Ra)2, -N(Rb)3+A', or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -N(Rb)2, -N(Rb)3+A’, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)2NRaNRbRb, -SxC(O)NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6alkenyl or OH; wherein Y is O or S; and wherein x is an integer from 1 to 4; and R4 is independently selected from -H, =0, -SRa, -ORa, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is O or S; and wherein x is an integer from 1 to 4. In any of these embodiments, A is selected from halide (fluorine, chlorine, bromine and iodine), hydroxyl and sulfate anions. Preferably A is selected from chlorine or bromine.

[0106] In some embodiments, R3 is selected from -H, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -N(Rb)2, -N(Rb)3+A', -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)2NRaNRbRb, -SxC(O)NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is 0 or S; and wherein x is an integer from 1 to 4; and R4 is independently selected from =0, -SRa, -0Ra, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -0Rb, -SRb, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SxC(O)NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, ora combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is 0 or S; and wherein x is an integer from 1 to 4. In any of these embodiments, A is selected from halide (fluorine, chlorine, bromine and iodine), hydroxyl and sulfate anions. Preferably A is selected from chlorine or bromine.

[0107] In some embodiments, R3 is selected from -H, or a C1-6 alkyl or alkenyl; and R4 is independently selected from =0, -SRa, -ORa, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SxC(O)NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is O or S; and wherein x is an integer from 1 to 4.

[0108] In some embodiments, R3 is selected from -H, or a C1-6 alkyl or alkenyl; and R4 is independently selected from =0, -SRa, -ORa, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -C(O)Rb, -C(O)YRb, C(S)Rb, -C(S)YRb, -S(O)ORb, -S(O)2ORb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6alkenyl; wherein Y is O or S.

[0109] In some embodiments, R3 is -H; and R4 is independently selected from =0, -SRa, -ORa, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -C(O)Rb, -C(O)YRb, C(S)Rb, -C(S)YRb, -S(O)ORb, -S(O)2ORb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Y is O or S. In some embodiments, R3 is -H; and R4 is independently selected from =0, -SRa, -ORa, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl. In some embodiments, R3 is -H; and R4 is independently selected from =0, -SH, -OH, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -OH, -SH, or a combination thereof. In some embodiments, R3 is -H; and R4 is independently selected from -SH, -OH, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -OH, -SH, or a combination thereof. In some embodiments, R3 is -H; and R4 is -OH, or a C1-6 alkyl optionally substituted by -OH.

[0110] In some embodiments, Xe is -N(Rb)2, -N(Rb)3+A', -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, or a combination thereof, wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Y is O or S; wherein A is an anion; n is an integer from 1 to 4; m is an integer from 1 to 4; R3 is selected from -H, or a C1-6 alkyl or alkenyl; and R4 is independently selected from =0, -SRa, -0Ra, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -C(O)Rb, -C(0)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is 0 or S; and wherein x is an integer from 1 to 4.

[0111] In some embodiments, X6 is -N(Rb)2, -N(Rb)3+A; -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, or a combination thereof, wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Y is O or S; wherein A is an anion; n is an integer from 1 to 4; m is an integer from 1 to 4; R3 is selected from -H, or a C1-6 alkyl or alkenyl; and R4 is independently selected from =0, -SRa, -0Ra, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -C(O)Rb, -C(0)YRb, C(S)Rb, -C(S)YRb, -S(O)ORb, -S(O)2ORb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Y is 0 or S.

[0112] In some embodiments, Xe is -N(Rb)2, -N(Rb)3+A’, -C(NRc)Rb, -C(NRb)NRbRb , or a combination thereof, wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein A is an anion; n is an integer from 1 to 4 and m is an integer from 1 to 4; R3 is -H; and R4 is independently selected from =0, -SRa, -0Ra, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -C(O)Rb, -C(O)YRb, C(S)Rb, -C(S)YRb, -S(O)ORb, -S(O)2ORb, ora combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Y is 0 or S.

[0113] In any of these embodiments, A is selected from halide (fluorine, chlorine, bromine and iodine), hydroxyl and sulfate anions. Preferably A is selected from chlorine or bromine.

[0114] In some embodiments, Xe is -N(Rb)3+A', wherein Rb is C1-6 alkyl or C1-6 alkenyl; wherein A is an anion; n is an integer from 1 to 4 and m is an integer from 1 to 4; R3 is -H; and R4 is independently selected from =0, -SRa, -ORa, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl.

[0115] In some embodiments, Xe is -N(Rb)3+A', wherein Rb is C1-6 alkyl or C1-6 alkenyl; wherein A is an anion; n is an integer from 1 to 4 and m is an integer from 1 to 4; R3 is -H; and R4 is independently selected from -SH, -OH, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -OH, -SH, or a combination thereof. In some embodiments, Xe is -N(Rb)3+A_, wherein Rb is C1-6 alkyl or C1-6 alkenyl; wherein A is an anion; n is an integer from 1 to 4 and m is an integer from 1 to 4; R3 is -H; and R4 is-OH, or a C1-6 alkyl optionally substituted by -OH.

[0116] In any of these embodiments, A is selected from halide (fluorine, chlorine, bromine and iodine), hydroxyl and sulfate anions. Preferably A is a halide anion, such as selected from chlorine or bromine.

[0117] In other embodiments, Xe is -ORb, -SRb, -C(O)Rb, -C(O)YRb, -C(S)Rb, -C(S)YRb, -S(O)ORb, -S(O)2ORb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; n is an integer from 1 to 4; m is an integer from 1 to 4; R3 is selected from -H, =N, -N(Ra)2, -N(Rb)3+A', or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -N(Rb)2, -N(Rb)3+A', -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)2NRaNRbRb, -SxC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, ora combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is O or S; and wherein x is an integer from 1 to 4; and R4 is independently selected from -H, or a C1-6 alkyl or alkenyl. In any of these embodiments, A is selected from halide (fluorine, chlorine, bromine and iodine), hydroxyl and sulfate anions. Preferably A is selected from chlorine or bromine.

[0118] In other embodiments, X6 is -ORb, -SRb, -C(O)YRb, -C(S)YRb, -S(O)ORb, or a combination thereof; wherein Rb is selected from H, C1-6 alkyl or C1-6 alkenyl; n is an integer from 1 to 4; m is an integer from 1 to 4; R3 is selected from -H, -N(Ra)2, -N(Rb)3+A’, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -N(Rb)2, -N(Rb)3+A’, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is O or S; and R4 is independently selected from -H, or a C1-6 alkyl or alkenyl. In any of these embodiments, A is selected from halide (fluorine, chlorine, bromine and iodine), hydroxyl and sulfate anions. Preferably A is selected from chlorine or bromine.

[0119] In other embodiments, Xe is -ORb, -SRb, -C(O)YRb, -C(S)YRb, or a combination thereof; wherein Rb is selected from H or C1-6 alkyl; n is an integer from 1 to 4; m is an integer from 1 to 4; R3 is selected from -H, -N(Ra)2, -N(Rb)3+A_, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -N(Rb)2, -N(Rb)3+A_, -C(NRc)Rb, -C(NRb)NRbRb, or a combination thereof; wherein Rb is selected from H or C1-6 alkyl wherein Rc is independently selected from H or C1-6 alkyl; and R4 is independently selected from -H, or a C1-6 alkyl. In any of these embodiments, A is selected from halide (fluorine, chlorine, bromine and iodine), hydroxyl and sulfate anions. Preferably A is a halide anion, such as chlorine or bromine.

[0120] It may be beneficial to functionalise a polymer backbone which is a polyamine, a polyamide, or a combination thereof, or a polyacrylate, polymethacrylate, polymaleate, polysulfonate, or a combination thereof, with one or more covalently bound functional groups represented by formula (III) as defined above; such embodiments have been shown to enhance the recovery of platinum group species, including rhodium and palladium cations, from a mixture of metal species (e.g. platinum group species and other d-block metal species such as nickel species), compared to the unfunctionalised polymer, i.e. the polyamine, polyamide or combination thereof, or the polyacrylates, polymethacrylate, polymaleate, polysulfonate, or combination thereof, without the functionalisation.

[0121] As well as enhancing %recovery, the functionalisation of the polymer backbone with a covalently bound functional group represented by formula (III) above, improved selectivity of the recovery for the target metal species, e.g. the platinum group species, over the non-target metal species, e.g. nickel.

[0122] The functionalisation with one or more covalently bound functional groups represented by formula (III) as defined above has also been shown to be beneficial for the recovery of target metal species with a variety of organic additives as defined herein, including organic additives with N-containing groups, S-containing groups, O-containing groups, and combinations thereof. Particular benefit has been observed for platinum group species when using an organic additive with a N-containing group (e.g. a N-heterocycle substituted with one or amino groups) or a combination of an N-containing group and a S-containing group (e.g. thioamide or the like) or a combination of an S-containing group and a O-containing groups (e.g. thiocarboxylic acid, a carboxylic acid and a thiol group, or the like). Such benefits are supported by the Examples described below in which 2-aminopyridine is employed as an exemplary N-heterocycle substituted with one or more amino groups, thiourea is employed as an exemplary thioamide, and thioglycolic acid is employed as an exemplary additive with a carboxylic acid and a thiol group.

[0123] An organic additive with a N-containing group (e.g. a N-heterocycle substituted with one or more amino groups as defined below and exemplified by 2-aminopyridine) was notably able to retain non-target metal species in solution, increasing the binding affinity of the target metal species for the functionalised polymer (e.g. a polyamine functionalised with a compound of formula (III) wherein Xe is -N(Rb)3+A_, Rb is C1-6 alkyl or C1-6 alkenyl; A is a halide anion; n is an integer from 1 to 4 and m is an integer from 1 to 4; R3 is -H; and R4 is independently selected from -SH, -OH, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -OH, -SH, or a combination thereof; such a functionalised polymer is exemplified below by GOMA). The organic additive with the N-containing group (e.g. 2-aminopyridine) was also found to be combinable with an organic additive with a N-containing group and an O-containing group (e.g. an amino carboxylic acid such as glycine) in order to improve efficiency of the metal recovery process without compromising selectivity. This further enhances the flexibility of the present disclosure to be modified according to the target metal species and / or functionalised polymer. N-heterocycles

[0124] In some embodiments the at least one covalently bound functional group of the polymer comprises a N-heterocycle. Suitable N-heterocycles include pyrrolyls, imidazolyls, triazolyls, tetrazolyls, pyridinyls, pyrimidyls, pyrazinyls, pyridazinyls, indolyls, benzimidazolyls, quinolinyls, isoquinolinyls, quinazolinyls, quinoxalinyls, and pyrazolyls. In preferred embodiments the N-heterocycle is selected from pyrrolyls, imidazolyls, triazolyls, tetrazolyls, pyridinyls, pyrimidyls, pyrazinyls, and pyridazinyls.

[0125] In some embodiments the N-heterocycle may be represented by formula (I) or (II) as defined in the appended claim set and below. ^X4 X3 X5 Xi wherein Xi, X2, X3, X4, and X5 in formula (I) and Xi, X2, X3, and X4 in formula (II) are independently C or N, provided that at least one is N; wherein Ri and R2 are independently selected from -H, =0, -SRa, -ORa, =S, =N, -N(Ra)2, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -N(Rb)2, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is O or S; wherein x is an integer from 1 to 4; wherein n is 0 or an integer from 1 to 8; and wherein m is 0 or an integer from 1 to 8.

[0126] In some embodiments, no more than three of Xi, X2, X3, X4, and X5 in formula (I) and no more than two of Xi, X2, X3, and X4 in formula (II) are N. In some embodiments, no more than two of Xi, X2, X3, X4, and X5 in formula (I) and no more than two of Xi, X2, X3, and X4 in formula (II) are N. In some embodiments, one of Xi, X2, X3, X4, and X5 in formula (I) and one of Xi, X2, X3, and X4 in formula (II) is N. In preferred embodiments,

[0127] In some embodiments, n is 0 and m is an integer from 1 to 8. In some embodiments, n is 0 and m is an integer from 1 to 6. In some embodiments, n is 0 and m is an integer from 1 to 4. In some embodiments, n is an integer from 1 to 8 and m is 0. In some embodiments, n is an integer from 1 to 6 and m is 0. In some embodiments, n is an integer from 1 to 4 and m is 0. In some embodiments, n is an integer from 1 to 8 and m is an integer from 1 to 8. In some embodiments, n is an integer from 1 to 6, and m is an integer from 1 to 6. In some embodiments, n is an integer from 1 to 4, and m is an integer from 1 to 4.

[0128] In some embodiments, no more than two of Xi, X2, X3, X4, and X5 in formula (I) and no more than two of Xi, X2, X3, and X4 in formula (II) are N, n is 0 and m is an integer from 1 to 4 or n is an integer from 1 to 4 and m is 0. In some embodiments, one of Xi, X2, X3, X4, and X5 in formula (I) and one of Xi, X2, X3, and X4 in formula (II) is N, n is 0 and m is an integer from 1 to 4 or n is an integer from 1 to 4 and m is 0.

[0129] In some embodiments, Ri is selected from -H, =N, -N(Ra)2, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -N(Rb)2, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)2NRaNRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb. or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is O or S; and wherein x is an integer from 1 to 4; and R2 is independently selected from -H, =0, -SRa, -ORa, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, ora combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is O or S; and wherein x is an integer from 1 to 4.

[0130] In some embodiments, no more than two of Xi, X2, X3, X4, and X5 in formula (I) and no more than two of Xi, X2, X3, and X4 in formula (II) are N, n is 0 and m is an integer from 1 to 4 or n is an integer from 1 to 4 and m is 0, wherein:Ri and R2 are each independently selected from -H, =0, -SRa, -ORa, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is O or S; and wherein x is an integer from 1 to 4.

[0131] In some embodiments, no more than two of Xi, X2, X3, X4, and X5 in formula (I) and no more than two of Xi, X2, X3, and X4 in formula (II) are N, n is 0 and m is an integer from 1 to 4 or n is an integer from 1 to 4 and m is 0, wherein: Ri and R2 are each independently selected from -H, =0, -SRa, -ORa, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -C(O)Rb, -C(O)YRb, -C(S)Rb, -C(S)YRb, -S(O)ORb, -S(O)2ORb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is O or S; and wherein x is an integer from 1 to 4.

[0132] In some embodiments, no more than two of Xi, X2, X3, X4, and X5 in formula (I) and no more than two of Xi, X2, X3, and X4 in formula (II) are N, n is 0 and m is an integer from 1 to 4 or n is an integer from 1 to 4 and m is 0, wherein: Ri and R2 are each independently selected from -H, =0, -SRa, -ORa, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -C(O)Rb, -C(O)YRb, -C(S)Rb, -C(S)YRb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is O or S; and wherein x is an integer from 1 to 4.

[0133] In some embodiments, no more than two of Xi, X2, X3, X4, and X5 in formula (I) and no more than two of Xi, X2, X3, and X4 in formula (II) are N, n is 0 and m is an integer from 1 to 4 or n is an integer from 1 to 4 and m is 0, wherein Ri and R2 are each independently selected from -H, =0, -SRa, -ORa, or =S. In some embodiments, one of Xi, X2, X3, X4, and X5 in formula (I) and one of Xi, X2, X3, and X4 in formula (II) is N, n is 0 and m is an integer from 1 to 4 or n is an integer from 1 to 4 and m is 0, wherein Ri and R2 are each independently selected from -H, =0, or =S.

[0134] In preferred embodiments, the N-heterocycle is represented by formula (I) with Xi, X2, X3, X4, X5, n, m, Ri and R2 defined as above. In particularly preferred embodiments, the N-heterocycle is represented by formula (I) with one of Xi, X2, X3, X4, and X5 as N, n is 0 and m is an integer from 1 to 4 or n is an integer from 1 to 4 and m is 0, wherein Ri and R2 are each independently selected from -H, =0, or =S.

[0135] It may be beneficial to functionalise a polymer backbone which is a polyamine, a polyamide, or a combination thereof, or a polyacrylate, polymethacrylate, polymaleate, polysulfonate, or a combination thereof, with one or more covalently bound functional groups represented by formula (I) or (II), especially where the functional group is represented by formula (I) as defined above; such embodiments have been shown to enhance the recovery of platinum group species, including rhodium and palladium cations, from a mixture of metal species (e.g. platinum group species and other d-block metal species such as nickel species), compared to the unfunctionalised polymer.

[0136] As well as enhancing %recovery, the functionalisation of the polymer backbone with a covalently bound functional group represented by formula (I) above improved selectivity of the recovery for the target metal species, e.g. the platinum group species, over the non-target metal species, e.g. nickel.

[0137] The functionalisation with a covalently bound functional group represented by formula (I) or (II) defined above, preferably formula (I) (e.g. with one of Xi, X2, X3, X4, and X5 as N, n is 0 and m is an integer from 1 to 4 or n is an integer from 1 to 4 and m is 0, wherein Ri and R2 are each independently selected from -H, =0, or =S, preferably Ri and R2 are each -H), has also been shown to be beneficial for the recovery of target metal species with a variety of organic additives as defined herein, including organic additives with N-containing groups, S-containing groups, O-containing groups, and combinations thereof. Particular benefit has been observed for platinum group species when using an organic additive with a combination of an N-containing group and S-containing group (e.g. thioamide), or the combination of an S-containing group and O-containing group (e.g. thioglycolic acid). In preferred embodiments the organic additive included at least one heteroatom which was different from the heteroatoms in the functionalised polymer. Such benefits are supported by the Examples described below wherein 2-PPEI is employed as an exemplary functionalised polymer having a covalently bound functional group represented by formula (I), thiourea is employed as an exemplary thioamide, and thioglycolic acid is employed as an exemplary additive with a carboxylic acid group and a thiol group. Benefits were further observed for platinum group species when using an organic additive which includes at least two N-containing groups exemplified by a N-heterocycle substituted with one or more amino groups (e.g. 2-aminopyridine).

[0138] As noted above, the at least one moiety or group of the functionalised polymer that binds the metal species comprises a heteroatom. Hence, when the covalently bonded functional group comprises a heteroatom, as exemplified by formulae (I), (II) and / or (III) above, the functionalised polymer may be bound to the metal species by the covalently bonded functional group. Additionally, the polymer backbone may include one or more moiety that binds the metal species. The nature of these interactions has been discussed elsewhere in this specification.

[0139] In some embodiments the polymer backbone of the functionalised polymer is a polyamine, a polyamide, or a combination thereof, and the at least one covalently bound functional group is represented by formula (III) above, wherein Xe is -N(Rb)2, -N(Rb)3+A_, -C(NRc)Rb, -C(NRb)NRbRb , or a combination thereof, wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein A is an anion (e.g. a halide anion); n is an integer from 1 to 4 and m is an integer from 1 to 4; R3 is -H; and R4 is independently selected from =0, -SRa, -0Ra, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -0Rb, -SRb, -C(O)Rb, -C(O)YRb, C(S)Rb, -C(S)YRb, -S(O)ORb, -S(O)2ORb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Y is 0 or S. In some embodiments, Xe is -N(Rb)3+A', wherein Rb is C1-6 alkyl or C1-6 alkenyl; wherein A is an anion; n is an integer from 1 to 4 and m is an integer from 1 to 4; R3 is -H; and R4 is independently selected from =0, -SRa, -0Ra, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -0Rb, -SRb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl. In some embodiments, Xe is -N(Rb)3+A', wherein Rb is C1-6 alkyl or C1-6 alkenyl; wherein A is an anion; n is an integer from 1 to 4 and m is an integer from 1 to 4; R3 is -H; and R4 is independently selected from -SH, -OH, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -OH, -SH, or a combination thereof. In some embodiments, Xe is -N(Rb)3+A; wherein Rb is C1-6 alkyl or C1-6 alkenyl; wherein A is an anion; n is an integer from 1 to 4 and m is an integer from 1 to 4; R3 is -H; and R4 is-OH, or a C1-6 alkyl optionally substituted by -OH. In any of these embodiments, A is selected from halide, hydroxyl and sulfate anion. Preferably A is selected from chlorine or bromine.

[0140] In some embodiments the polymer backbone of the functionalised polymer is a polyamine, a polyamide, or a combination thereof, and the at least one covalently bound functional group is represented by formula (I) or formula (II) above, wherein no more than two of Xi, X2, X3, X4, and X5 in formula (I) and no more than two of Xi, X2, X3, and X4 in formula (II) are N, n is 0 and m is an integer from 1 to 4 or n is an integer from 1 to 4 and m is 0, wherein: Ri and R2 are each independently selected from -H, =0, -SRa, -ORa, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -C(O)Rb, -C(O)YRb, -C(S)Rb, -C(S)YRb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is O or S; and wherein x is an integer from 1 to 4. In some embodiments, no more than two of Xi, X2, X3, X4, and X5 in formula (I) and no more than two of Xi, X2, X3, and X4 in formula (II) are N, n is 0 and m is an integer from 1 to 4 or n is an integer from 1 to 4 and m is 0, wherein Ri and R2 are each independently selected from -H, =0, -SRa, -ORa, or =S. In some embodiments, one of Xi, X2, X3, X4, and X5 in formula (I) and one of Xi, X2, X3, and X4 in formula (II) is N, n is 0 and m is an integer from 1 to 4 or n is an integer from 1 to 4 and m is 0, wherein Ri and R2 are each independently selected from -H, =0, or =S.

[0141] In preferred embodiments, the N-heterocycle is represented by formula (I) with Xi, X2, X3, X4, X5, n, m, Ri and R2 defined as above. In particularly preferred embodiments, the N-heterocycle is represented by formula (I) with one of Xi, X2, X3, X4, and X5 as N, n is 0 and m is an integer from 1 to 4 or n is an integer from 1 to 4 and m is 0, wherein Ri and R2 are each independently selected from -H, =0, or =S.

[0142] In any of the above embodiments, the polymer backbone of the functionalised polymer may be selected from a polymer derived from aziridine (e.g. polyethyleneimine), polyvinylamine, polyallylamine, chitosan, polylysine, polyarginine, or a combination thereof. Alternatively, the polymer backbone of the functionalised polymer may be selected from a polyacrylate, polymethacrylate, polymaleate, polysulfonate, or a combination thereof. Organic Additive

[0143] By the term “organic additive” is meant a hydrocarbyl substituted by at least one heteroatom-containing group, wherein the organic additive comprises at least one group that binds a metal species. The term “hydrocarbyl” means a univalent group formed by removing a hydrogen from a hydrocarbon. A heteroatom-containing group and a group that binds a metal species is as defined above for the functionalised polymer. The identity of the heteroatom(s) in the organic additive relative to the metal species and / or functionalised polymer has also been discussed elsewhere in this specification.

[0144] The organic additive thus includes a covalent carbon bond, and is typically derived from small organic molecules consisting of fewer than five heteroatom-containing groups. The organic additive plays a crucial role in enhancing metal recovery and selectivity, primarily by controlling the binding affinity of metal species for functionalised polymers. The organic additive has the potential to enhance the recovery and / or selectivity towards the target metal species. Alternatively, it can bind to non-target metals, ensuring their retention in the solution, even after the addition of the precipitant. The organic additive can therefore either increase or decrease the affinity of a metal species for the functionalised polymer. The present disclosure is not limited in this respect.

[0145] As used herein, the term “small” is meant a weight average molecular weight, as measured by mass spectrometry (e.g. El), of less than about 1000 Da, such as from about 50 Da to about 1000 Da.

[0146] In some embodiments the organic additive comprises at least one group that binds the metal species in the aggregate, i.e. the target metal species. In some embodiments the organic additive comprises at least one group that binds the covalently bound functional group of the polymer. Hence, the functionalised polymer may be bound to the organic additive, the organic additive being bound to the metal species. Additionally, and alternatively, the functionalised polymer may be bound to the metal species, and the organic additive may be bound to the functionalised polymer.

[0147] In some embodiments the organic additive comprises at least one group that binds a non-target metal species. In some embodiments multiple organic additives may be employed comprising an organic additive that binds to non-target metal species and an organic additive that binds to target metal species and / or the functionalised polymer.

[0148] As noted above, groups that bind metal species may be selected according to the metal species that it is desired to recover (target) and / or retain in solution (non-target). The skilled person is aware of suitable groups in this respect, and is readily able to select a particular functional group for binding to a particular metal species as well as obtain or synthesise an organic additive which bears that particular group for use in accordance with the present disclosure. Suitable organic additives with at least one group that binds a metal species are known or commercially available. The skilled person is also readily able to synthesise organic additives bearing such groups using routine synthesis methods.

[0149] The coordination between the organic additive and the functionalised polymer is not limited. In some embodiments this coordination is electrostatic, via the heteroatom-containing group on the organic additive, and the functionalised group on the polymer backbone, but is otherwise not limited; the electrostatic coordination may be via dipole-dipole interactions, London dispersion forces, hydrogen bonding, ionic bonding, or a combination thereof. In some embodiments the organic additive does not form a covalent bond with the polymer; it is therefore distinguishable from the covalently bound functional group.

[0150] The coordination between the organic additive and the metal species - target or nontarget - is similarly not limited; it may electrostatic, or covalent, where covalent includes coordinative covalent bonding. When the coordination is electrostatic, it may be via dipole-dipole interactions, London dispersion forces, hydrogen bonding, ionic bonding, or a combination thereof; when the coordination is covalent, the organic additive may be an electron-pair donor or an electron-pair acceptor with the metal species, typically the organic additive is an electronpair donor.

[0151] Suitable heteroatom-containing groups are known in the art and include, but are not limited to, the following O-containing, S-containing, N-containing and P-containing groups. The inclusion of these groups in the organic additive may be determined by the metal species it is desired for the organic additive to bind to, the functionalisation of the polymer backbone, and whether the organic additive binds to the functionalised polymer. Having identified the metal species and the functionalised polymer, the skilled person would be readily able to prepare or provide a suitable organic additive for the present disclosure.

[0152] Example O-containing groups include: OH, ethers, carboxyls, carbonyls, sulfonic acids, sulfinic acids, thioketones, thials, thioesters, oximes, hydrazides, carbazides, furanyls, oxazolyls, isoxazolyls, benzofuranyls, quinoxalinyls, phosphoric acids, phosphinic acids, phosphonic acids; preferably OH, carboxyls, carbonyls;

[0153] Example S-containing groups include: sulfonic acids, sulfinic acids, sulfhydryls, sulfides, thioketones, thials, thioesters, thioamides, thienyls, thiazolyls, benzothiophenyls, thiophenyls; preferably sulfonic acids, sulfinic acids, sulfhydryls, thioketones, thials, thioesters, thioamides;

[0154] Example P-containing groups include: phosphoric acids, phosphinic acids, phosphonic acids; and

[0155] Example N-containing groups include: thioamides, cyano groups, amino groups, imino groups, imides, amides, amidines, oximes, hydrazides, carbazides, quaternary nitrogen groups, pyrrolyls, oxazolyls, isoxazolyls, thiazolyls, imidazolyls, triazolyls, tetrazolyls, pyridinyls, pyrimidyls, pyrazinyls, pyridazinyls, indolyls, benzimidazolyls, quinolinyls, isoquinolinyls, quinazolinyls, quinoxalinyls, and pyrazolyls; preferably thioamides, amino groups, imino groups, amides, imides, amidines and N-heterocycles including pyrrolyls, triazolyls, tetrazolyls, pyridinyls, pyrimidyls, pyrazinyls, pyridazinyls.

[0156] In some embodiments the at least one heteroatom-containing group of the organic additive is selected from a carboxyl groups, a carbonyl group, a sulfonic acid group, a sulfinic acid group, a sulfhydryl group, a thioketone group, a thial group, a thioester group, a thioamide group, a phosphoric acid group, a phosphinic acid group, a phosphonic acid group, an amino group, an imino group, an imide group, an amide group, an amidine group, a N-heterocycle group, and a combination thereof. Suitable N-heterocycles include pyrrolyls, imidazolyls, triazolyls, tetrazolyls, pyridinyls, pyrimidyls, pyrazinyls, pyridazinyls, indolyls, benzimidazolyls, quinolinyls, isoquinolinyls, quinazolinyls, quinoxalinyls, and pyrazolyls.

[0157] In some embodiments the at least one heteroatom-containing group of the organic additive is selected from a carboxyl group, a carbonyl group, a sulfonic acid group, a sulfinic acid group, a sulfhydryl group, a thioketone group, a thial group, a thioester group, a thioamide group, an amino group, an imino group, an amide group, amidine groups, a N-heterocycle group, and a combination thereof. Suitable N-heterocycles include pyrrolyls, imidazolyls, triazolyls, tetrazolyls, pyridinyls, pyrimidyls, pyrazinyls, pyridazinyls, indolyls, benzimidazolyls, quinolinyls, isoquinolinyls, quinazolinyls, quinoxalinyls, and pyrazolyls.

[0158] In some embodiments the at least one heteroatom-containing group of the organic additive is selected from a carbonyl group, a thioamide group, an amino group, a sulfhydryl group, a N-heterocycle group (e.g. pyridine), and a combination thereof. For example, the O-containing group (carbonyl) may be combined with a N-containing group (thioamide, amino, N-heterocycle). In a preferred embodiment, the organic additive comprises a carbonyl group and an amino group. Another example is the S-containing group (thioamide or sulfhydryl) may be combined with a N-containing group (thioamide, amino, N-heterocycle) or an O-containing group (carbonyl). In another preferred embodiment, the organic additive comprises a thioamide, a sulfhydryl and a carbonyl group. Another example is the N-containing group may be combined with another N-containing group (e.g. N-heterocycle and an amino group).

[0159] The organic additive may be a mono-functional group, i.e. it may include one heteroatom-containing group such as a sulfonic acid or the like. In some embodiments where the organic additive is able to coordinate with both the polymer and a metal species, it may be at least a bidentate or bi-functional molecule. The organic additive may coordinate with the functionalised polymer and / or metal species via two or more atoms and in various embodiments may therefore be a bidentate / bi-functional, tridentate / tri-functional, or polydentate / poly-functional molecule.

[0160] In some embodiments the organic additive includes at least two heteroatom-containing groups. The at least two heteroatom-containing groups may differ from each other by the heteroatom and / or the coordination environment. For example, a N-heterocycle may be combined with an amino group, these groups differ from each other by the coordination environment of the N atom. In contrast, a sulfhydryl group may be combined with a carbonyl group, these two heteroatom-containing groups differing from each other by the type of heteroatom. A thioamide also has at least two heteroatom-containing groups that differ from each other by type (=S and two amino groups).

[0161] In some embodiments the at least two heteroatom-containing groups are N-containing groups. Suitable N-containing groups are defined above.

[0162] In some embodiments the at least two N-containing groups of the organic additive are selected from amino groups, imino groups, amide groups, imide groups, diazonium compounds, amidine groups, hydrazide groups, carbazide groups, cyano groups, oxime groups, thioamide groups, and N-heterocycles. Suitable N-heterocycles are defined above. In preferred embodiments, the at least two N-containing groups are a N-heterocycle (e.g. pyridine) substituted by one or more amino, imino, amide, imide, amidine, hydroazide, carbazide, cyano, oxime, or thioamide groups, or a thioamide. An example is a 2-aminopyridine as demonstrated below.

[0163] Such organic additives may be beneficial when combined with a polymer backbone comprising an aliphatic or aromatic hydrocarbon functional group as defined above. Particular benefits in recovery and selectivity with such functionalised polymers have been observed when the organic additive is a thioamide, or a N-heterocycle (e.g. pyridine) substituted by one or more amino, imino, cyano or thioamide groups, for recovery of d-block, e.g. platinum group species.

[0164] Such organic additives may also be beneficial when combined with a polymer backbone comprising a functional group of formula (III) defined above. Specifically, formula (III) wherein Xg is -N(Rb)3+A_, wherein Rb is C1-6 alkyl or C1-6 alkenyl; wherein A is an anion; n is an integer from 1 to 4 and m is an integer from 1 to 4; R3 is -H; and R4 is independently selected from =0, -SRa, -ORa, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl. A thioamide, and a substituted N-heterocycle organic additive as defined above have also been found to be beneficial when combined with a polymer backbone having a functional group of formula (I) defined above with one of Xi, X2, X3, X4, and X5 as N, n is 0 and m is an integer from 1 to 4 or n is an integer from 1 to 4 and m is 0, wherein Ri and R2 are each independently selected from -H, =0, or =S.

[0165] In other embodiments the at least two heteroatom-containing groups are (i) a N-containing group and a S-containing group, or (ii) a S-containing group and an O-containing group. Suitable N-containing, S-containing, and O-containing groups are defined above.

[0166] In some embodiments the N-containing group may be selected from amino groups, imino groups, amide groups, imide groups, diazonium compounds, amidine groups, hydrazide groups, carbazide groups, cyano groups, oxime groups, thioamide groups, and N-heterocycles. Suitable N-heterocycles are defined above. In some embodiments the S-containing group may be selected from sulfonic acid groups, sulfinic acid groups, thioketone groups, thial groups, thioester groups, thioamide groups, and sulfhydryl groups. In some embodiments, the O-containing group is selected from hydroxyl groups, carboxyl groups, and carbonyl groups.

[0167] In preferred embodiments the at least two heteroatom-containing groups are a N-containing group and a S-containing group, wherein the N-containing group is selected from amino groups, imino groups, amide groups, imide groups, cyano groups, and N-heterocycles, and wherein the S-containing group is selected from thioketones, thioesters, thioamides, and sulfhydryl groups. Suitable N-heterocycles are defined above (e.g. pyridine). In other preferred embodiments the at least two heteroatom-containing groups are a N-containing group and a O-containing group, wherein the N-containing group is selected from amino groups, imino groups, amide groups, imide groups, cyano groups, and N-heterocycles, and wherein the O- containing group is selected from carboxyl groups and carbonyl groups.

[0168] Such organic additives may be beneficial when combined with a functionalised polymer which is a reaction product of a polymer backbone and an aliphatic or aromatic hydrocarbon functional group as defined above. Particular benefits in recovery and selectivity with such functionalised polymers have been observed when the organic additive is a thioamide (e.g. thiourea) or a thioglycolic acid. Such organic additives may also be beneficial when combined with functionalised polymer which is a reaction product of a polymer backbone and a functional group of formula (I) or (III) defined above. Specifically formula (III), wherein X6 is -N(Rb)3+A_, wherein Rb is C1-6 alkyl or C1-6 alkenyl; wherein A is an anion; n is an integer from 1 to 4 and m is an integer from 1 to 4; R3 is -H; and R4 is independently selected from =0, -SRa, -ORa, =S, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl. Specifically formula (I) with one of Xi, X2, X3, X4, and X5 as N, n is 0 and m is an integer from 1 to 4 or n is an integer from 1 to 4 and m is 0, wherein Ri and R2 are each independently selected from -H, =0, or =S.

[0169] In some embodiments the organic additive includes at least three heteroatom-containing groups, wherein the at least three heteroatom-containing groups are a N-containing group, a S- containing group and an O-containing group. In some embodiments, the N-containing group is selected from amino groups, imino groups, amide groups, imide groups, diazonium compounds, amidine groups, hydrazide groups, carbazide groups, cyano groups, oxime groups, thioamide groups, and N-heterocycles; the S-containing group is selected from sulfonic acid groups, sulfinic acid groups, thioketone groups, thial groups, thioester groups, thioamide groups, and sulfhydryl groups; and the O-containing group is selected from hydroxyl groups, carboxyl groups, and carbonyl groups. In preferred embodiments, the N-containing group is an amino group, an amide group, an imino group or a N-heterocycle, wherein the S-containing group is a thioamide group, and wherein the O-containing group is a carboxyl group.

[0170] In addition to the above heteroatom-containing groups, whether to bind the metal species or interact with the functionalised polymer, the organic additive may comprise a hydrocarbon moiety. This hydrocarbon moiety may in addition to any carbon / hydrogen in the heteroatom-containing groups. The hydrocarbon moiety comprises an aliphatic hydrocarbon group or an aromatic hydrocarbon group and in preferred embodiments is a C1-C12 hydrocarbyl, for example a C1-C12 alkyl, alkenyl, aryl, alkaryl, or cycloalkyl. The terms alkyl, alkenyl, aryl, alkaryl, and cycloalkyl are defined hereinabove.

[0171] In various embodiments, the organic additive is a C1-C12 hydrocarbyl substituted by the at least one heteroatom-containing group. In some embodiments the organic additive is a C1-C12 hydrocarbyl substituted by the at least two heteroatom-containing groups. For example, the organic additive may be a C1-12 hydrocarbyl substituted by at least one sulfhydryl, amine, imino, amide, carboxyl or carbonyl group.

[0172] In various embodiments, the organic additive is a thioamide, a C1-C12 hydrocarbyl substituted by at least two heteroatom-containing groups selected from amine groups, imino groups, amide groups, sulfhydryls, carboxyl or carbonyl groups, a N-heterocycle substituted with one or more amino, imino, amide, imide, amidine, hydroazide, carbazide, cyano, oxime, or thioamide groups, or a combination thereof. In preferred embodiments, the C1-C12 hydrocarbyl is substituted by at least two heteroatom-containing groups in which the heteroatoms are different.

[0173] In various embodiments, the organic additive is a thioamide, a C1-C12 hydrocarbyl substituted by at least two heteroatom-containing groups selected from amine groups, imino groups, amide groups, sulfhydryls, carboxyl or carbonyl groups, a N-heterocycle substituted with one or more amino, imino, cyano or thioamide groups, ora combination thereof. In preferred embodiments, the C1-C12 hydrocarbyl is substituted by at least two heteroatom-containing groups in which the heteroatoms are different. Metal Species

[0174] The term “metal species” is used herein to refer to metal or metallic ions. A metal or metallic ion is a metal-containing ion. This may be a monatomic metal ion or a polyatomic ion in which at least one of the atoms is a metal ion. Thus, a metallic ion may be a metal anion or a metal cation, or a complex anion that comprises a metal, such as a chromate, dichromate, ferricyanide and permanganate, or indeed a complex cation which comprises a metal. In other words, the metal may be bound to a ligand(s), e.g. covalent, coordinative or electrostatically bound, when present in the metal species.

[0175] The valency of the metal species is not limited. The metal species may be monovalent, e.g. a monocation or a monoanion, or it may have a valency of two or more including dications, trications, tetracations, pentacations, hexacations, dianions, trianions, tetranions, pentanions and hexanions. The present disclosure is particularly beneficial for the removal of one or more specific metal species from a solution, i.e. target metal species. Consequently, the valency of the metal species may be a mixture and not defined by a single value, for example a mixture of monovalent and divalent or higher species.

[0176] In various embodiments, the metal species comprises a metallic cation or a mixture thereof, preferably a d-block metal cation or a mixture thereof.

[0177] In some embodiments the metal of the metal species is selected from scandium, vanadium, chromium, manganese, cobalt, nickel, copper, yttrium, niobium, ruthenium, rhodium, silver, cadmium, tungsten, rhenium, osmium, iridium, platinum, gold, mercury, or a mixture thereof. In preferred embodiments the metal of the metal species is selected from scandium, vanadium, chromium, manganese, yttrium, niobium, ruthenium, rhodium, silver, cadmium, tungsten, rhenium, osmium, iridium, platinum, gold, mercury, or a mixture thereof.

[0178] The present disclosure is particularly beneficial for the recovery of d-block metal species including platinum group species, preferably platinum group cations, from mixed metal solutions, preferably mixed metal cation solutions. The removal and recovery of platinum group species is of particular interest, specifically from waste streams during the manufacture and use of catalysts in pharmaceutical processes or the like. Hence, in various embodiments, the metal species in the product of the present disclosure (namely the target metal species) comprises a platinum group cation, or a mixture thereof. The process of the present disclosure may similarly be for removing platinum group species from a solution.

[0179] The term “platinum group species” is used herein to refer to the six platinum group metals, namely ruthenium, rhodium, palladium, osmium, iridium, and platinum, or a combination thereof. The present disclosure is able to effectively and selectively recover platinum group species from a mixture of metal species, the mixture including, but not limited to, e.g. one or more other d-block metals such as nickel, copper, or iron. The present disclosure is also able to effectively and selectively recover platinum group species from a mixture of metal species, the mixture including but not limited to, e.g. one or more other metals (i.e. not necessarily d-block metals). Hence, the process of the present disclosure may be for removing platinum group species from a solution, where the solution comprises target platinum group species, a solvent, and optionally non-target metal species, wherein the non-target metal species is different from the target platinum group species, preferably wherein the non-target metal species is a d-block metal species.

[0180] By the term “target” is meant the metal species to which the recovery process is directed.

[0181] By the term “non-target” is meant any other metal species in solution with the target metal species. The “non-target” metal species may otherwise be referred to as “contaminant” metal species.

[0182] For example, an industrial waste stream may include palladium species, rhodium species and nickel species, and the recovery process may target the palladium species and the rhodium species over the nickel species. Hence, in such embodiments, the target metal species comprises palladium and rhodium, and the non-target metal species comprises nickel.

[0183] The functional group on the polymer backbone and the organic additive exerts a significant influence on both the recovery and selectivity. The present disclosure is able to selectively recover d-block metal species including platinum group species, from mixed metal species solutions. Precipitant

[0184] The term precipitant as used herein refers to a compound that causes precipitation of at least the polymer-organic additive-target metal species (i.e. complex) from solution. The manner in which the precipitant causes precipitation is not limited. In various embodiments, the precipitant is therefore a compound that causes the complex formed from the functionalised polymer, the organic additive, and the target metal species, to precipitate from the solution. The precipitant comprises at least one hydrophilic moiety and at least one hydrophobic moiety, and at least one group that binds the functionalised polymer and / or the target metal species. The at least one group that binds the functionalised polymer and / or the target metal species may be the hydrophilic moiety or the hydrophobic moiety. In preferred embodiments the at least one group that binds the target metal species is the hydrophilic moiety and the at least one group that binds the functionalised polymer is the hydrophobic moiety. The nature of the binding is not limited; the precipitant may bind to functionalised polymer and / or the target metal species either covalently or electrostatically to induce precipitation.

[0185] The formation of micelle-like structures involving the precipitant and its hydrophilic / hydrophobic moieties is discussed above. Suitable hydrophobic moieties will be known to the person skilled in the art. The hydrophobic group is often referred to as the tail group. The tail usually comprises a hydrocarbon chain, i.e. a chain comprising carbon atoms, which may be branched, linear or aromatic in nature.

[0186] The at least one group that binds the target metal species comprises a heteroatom. The heteroatom may otherwise be referred to as a “donor atom” and is selected from sulfur, phosphorus, nitrogen, and oxygen. Consequently, the at least one group on the precipitant that binds the target metal species comprises at least one sulfur atom, phosphorus atom, nitrogen atom, oxygen atom, or a combination thereof. In preferred embodiments the at least one group on that binds the target metal species comprises at least one nitrogen atom, sulphur atom, oxygen atom, or a combination thereof.

[0187] As will be understood by the person skilled in the art, this means that the precipitant could be a polymer which is anionic or cationic when in aqueous solution and thus the polyelectrolytic polymer backbone as defined above for the functionalised polymer, the charge of the polyelectrolytic polymer backbone in aqueous solution being of opposite charge to the complex-forming functionalised polymer described herein and / or the target metal species. Examples of polymers which are anionic in aqueous solution include, but are not limited to, polymers with carboxyl groups including polyolefins substituted with carboxyl groups, polyesters substituted with carboxyl groups, polyamides substituted with carboxyl groups, and polysulfides with carboxyl groups, polymers with sulfonic acid groups including polyolefins substituted with sulfate or sulfonate groups, polyesters substituted with sulfate or sulfonate groups, polysulfides substituted with sulfate or sulfonate groups, and poly(sodium styrene sulfonate). Examples of polymers which are cationic in aqueous solution include, but are not limited to, polymers with N-containing groups including organic polymers with one or more amine, imine or N-heterocycle groups, such as aliphatic amine groups. The polymer may be a homopolymer, copolymer or an interpolymer.

[0188] In some embodiments the precipitant is a polymer which is cationic when in aqueous solution (e.g. a polyamine as defined above).

[0189] In various embodiments the precipitant is a surfactant. The term surfactant, as used herein, refers to an amphiphilic compound comprising the hydrophobic moiety defined above and a hydrophilic moiety. The hydrophilic moiety is often referred to as the head group and usually comprises an ionic functional group, such as an anionic functional group or a cationic functional group, or a non-ionic group. Surfactants are widely used to reduce the surface tension of a liquid to which it is added.

[0190] When the precipitant is a surfactant, it can be a non-ionic surfactant or an ionic surfactant. Non-ionic surfactants are known in the art. The precipitant is typically an ionic surfactant. The ionic surfactant may comprise a hydrocarbon chain terminating in an ionic functional group. In such embodiments, the surfactant may be an anionic, amphoteric, or cationic surfactant, or mixtures thereof. In preferred embodiments the precipitant is selected from anionic surfactants, cationic surfactants, and mixtures thereof.

[0191] The precipitant comprises at least one group that binds the target metal species and / or the functionalised polymer. Consequently, when the precipitant is a surfactant, the type of surfactant will depend on whether the target metal species and / or the polymer backbone of the functionalised polymer comprises a positive charge, a negative charge, or a combination thereof. Generally, when the target metal species and / or the polymer backbone of the functionalised polymer are positively charged, the surfactant comprises an anionic surfactant or a polymer which is anionic when in aqueous solution. On the other hand, when the target metal species and / or the polymer backbone of the functionalised polymer are negatively charged, the surfactant comprises a cationic surfactant or a polymer which is cationic when in aqueous solution.

[0192] For example, when the polymer backbone of the functionalised polymer is cationic when in aqueous solution, the precipitant may be selected from an anionic surfactant, a polymer which is anionic in aqueous solution, and mixtures thereof. Alternatively, when the polymer backbone of the functionalised polymer is anionic when in aqueous solution, the precipitant may be selected from a cationic surfactant, a polymer which is cationic in aqueous solution, and mixtures thereof.

[0193] Suitable anionic and cationic surfactants, and polyelectrolytic polymers are known in the art and described herein. An anionic surfactant is typically a compound comprising a hydrocarbon chain terminating in an anionic functional group. A cationic surfactant is typically a compound comprising a hydrocarbon chain terminating in a cationic functional group. The hydrocarbon chain may be an unsubstituted C5-C35 alkyl group for each type of surfactant.

[0194] The anionic surfactant may comprise an anionic functional group selected from a sulfate, sulfonate, phosphate, phosphate and carboxylate group, and a C5-C35 alkyl, C6-C36 aryl, or C7-C37 alkaryl group. In preferred embodiments, the anionic surfactant comprises an anionic functional group selected from a sulfate, sulfonate, phosphate, phosphate and carboxylate group, and a C5-C20 alkyl, C6-C24 aryl, or C7-C25 alkaryl group. For instance, the anionic surfactant may be a C5-C20 alkyl or C7-C37 alkaryl sulfate or sulfonate.

[0195] As used herein, the term “sulfate” represents a group of formula: -SC>42'. As would be understood by the skilled person, a sulfate group can exist in protonated and deprotonated forms (for example, -SOtFT or -SCU2-), and in salt forms (for example, -(SO4)X2 or -(SO4)X, wherein X is a monovalent or divalent cation). X may for instance be an alkali metal cation or a cationic alkaline earth metal. Thus, X may be Na+, K+, Ca2+ or Mg2+, for instance.

[0196] As used herein, the term “sulfonate” or “sulfonic acid” represents a group of formula: -S(=O)2O'. As would be understood by the skilled person, a sulfonate group can exist in protonated and deprotonated forms (for example, -S(O)2OH or -S(=0)2O), and in salt forms (for example, -(S(0)20)X or-(S(O)2O)X2, wherein X is a monovalent or divalent cation). X may for instance be an alkali metal cation or a cationic alkaline earth metal. Thus, X may be Na+, K+, Ca2+ or Mg2+, for instance.

[0197] As used herein, the term “phosphate” represents a group of formula: -PO43'. As would be understood by the skilled person, a phosphate group can exist in protonated and deprotonated forms (for example, -PCUH2’, -PO4H2' or -PO43'), and in salt forms (for example, -(PO4)Xb or -(PO4)sX2, wherein X is a monovalent or divalent cation ). X may for instance be an alkali metal cation or a cationic alkaline earth metal. Thus, X may be Na+, K+, Ca2+ or Mg2+, for instance.

[0198] As used herein, the term “phosphonate” represents a group of formula: -PO(OR)2', wherein R is, for example, hydrogen or a Ci-Ce alkyl group. As would be understood by the skilled person, a phosphonate group can exist in protonated and deprotonated forms (for example, -PO(OR)2H of -PO(OR)2'), and in salt forms (for example, -PO(OR)2X or -PO(OR)X, wherein X is a monovalent or divalent cation). X may for instance be an alkali metal cation or a cationic alkaline earth metal. Thus, X may be Na+, K+, Ca2+ or Mg2+, for instance.

[0199] As used herein, the term “carboxylate” represents a group of the formula: -C(=0)O or-COO. As would be understood by the skilled person, a carboxylate group can exist in protonated and deprotonated forms (for example, -C(=O)OH and -C(=O)O'), and in salt forms (for example, -C(=O)OX or-(C(=O)O)2X, wherein X is a monovalent or divalent cation). X may for instance be an alkali metal cation or a cationic alkaline earth metal. Thus, X may be Na+, K+, Ca2+ or Mg2+, for instance.

[0200] The anionic surfactant may further comprise a cation. The cation may be selected from a nitrogen-containing cation, e.g. ammonium, or a group I cation, e.g. sodium or potassium. In various embodiments, the anionic surfactant is selected from ammonium lauryl sulphate, dioctyl sodium sulfosuccinate, potassium lauryl sulfate, soap, sodium dodecyl sulphate (SDS), sodium dodecylbenzenesulphonate, sodium laureth sulphate, sodium lauroyl sarcosinate, sodium myreth sulphate, sodium pareth sulfate, and sodium stearate. In preferred embodiments the cation is a group I cation, e.g. sodium or potassium. For example, the anionic surfactant may be selected from dioctyl sodium sulfosuccinate, potassium lauryl sulfate, sodium dodecyl sulphate (SDS), sodium dodecylbenzenesulphonate, sodium laureth sulphate, sodium lauroyl sarcosinate, sodium myreth sulphate, sodium pareth sulfate, and sodium stearate.

[0201] The cationic surfactant may comprise a cationic functional group and a C5-C35 alkyl, Ce-C36 aryl, or C7-C37 alkaryl group. In preferred embodiments, the cationic surfactant comprises a cationic functional group, and a C5-C20 alkyl, C6-C24 aryl, or C7-C25 alkaryl group. The cationic functional group may comprise a quaternary nitrogen or may be a nitrogen-containing group wherein the nitrogen is not a quaternary nitrogen. The latter is a group wherein the nitrogens are not quaternary nitrogens, such as protonated monodentate primary, secondary and tertiary amino groups, i.e. -NH3, -NHR2, and -NH2R, and protonated bidentate secondary and tertiary amines, i.e. -N+RH- and -NH2-. As the skilled person will appreciate, the cationic nitrogencontaining groups will usually only be cationic if in acidic conditions (i.e. pH of less than 7).

[0202] When the cationic surfactant comprises a quaternary nitrogen, the quaternary nitrogen typically has the formula: (NRiR2RaR4)+, wherein Ri, R2, R3 and R4 are independently selected from a substituted or unsubstituted alkyl group or a substituted or unsubstituted alkenyl group. Usually, when the cationic surfactant comprises a quaternary nitrogen, the quaternary nitrogen typically has the formula: (NRiR2RsR4)+, wherein Ri, R2, R3 and R4 are independently selected from a substituted or unsubstituted C1-C18 alkyl group. In preferred embodiments, Ri, R2 and R3 are independently selected from a substituted or unsubstituted Ci-Ce alkyl group and R4 is a substituted or unsubstituted C10-C18 alkyl group. For instance, Ri, R2 and R3 are independently selected from a substituted or unsubstituted C1-C3 alkyl group such as methyl or ethyl, for instance methyl, and R4 is a substituted or unsubstituted C10-C18 alkyl group, for instance R4 a substituted or unsubstituted C15-C18 alkyl group.

[0203] The cationic surfactant may, for instance, comprise an anion, for instance a halide such as a fluoride, chloride, bromide or iodide anion. Typically, the anion is a chloride anion or a bromide anion, for instance a bromide anion.

[0204] The cationic surfactant may, for instance, be selected from a benzalkonium chloride, Myristyltrimethylammonium bromide (Ci4TAB or MTAB) and Myristyltrimethylammonium chloride. The cationic surfactant may, for instance, be Myristyltrimethylammonium bromide (Ci4TAB, or MTAB).

[0205] When the functionalised polymer comprises a combination of acidic and basic groups, the precipitant may comprise an amphoteric surfactant. In various embodiments, the amphoteric surfactant is selected from the group consisting of hydrocarbyl-amphoacetates, alkenyl-amphoacetates, hydrocarbyl-amphodiacetates, alkenyl-amphodiacetates, hydrocarbylampho-propionates, hydrocarbylampho-diproprionates, hydrocarbylamphohydroxypropyl sultaines, and mixtures thereof. In various embodiments, the hydrocarbyl and alkenyl groups are Ce to C24, Cs to C24, or C10 to C20, hydrocarbyl or alkenyl groups. Typically, the amphoteric surfactant has a counter-ion of an alkali metal such as sodium or potassium, or an ammonium ion. In preferred embodiments, the amphoteric surfactant has an alkali metal counter-ion, and more preferably the counter-ion is sodium.

[0206] In various embodiments the amphoteric surfactant is a hydrocarbyl-amphoacetate salt, preferably a fatty acid amphoacetate. The fatty acid or salt thereof may be a Ce-C24 fatty acid or salt thereof, or a mixture thereof. The fatty acid or salt thereof may be saturated or unsaturated. When unsaturated, the unsaturated fatty acid or salt thereof may be mono- or di-unsaturated. The unsaturated fatty acid or salt thereof may comprise cis- or trans- double bonds or mixtures thereof. In further embodiments, the fatty acid or salt thereof is a C12-C18 monounsaturated fatty acid or salt thereof. Examples of fatty acids include stearic acid, ricinoleic acid, oleic acid, eladic acid, petrolselinic acid, palmitic acid, erucic acid, behenic acid, lauric acid, myristic acid, or linoleic acid.

[0207] In preferred embodiments, the amphoteric surfactant comprises a cocoamphoacetate. The counter-ion of the cocoamphoacetate is preferably sodium. Sodium cocoamphoacetate is commercially available, for example under the trade name Dehyton® MC (BASF) or Amphosol® 1C (Stepan®). Such commercial preparations are typically solutions of sodium cocoamphoacetate, typically containing from about 30 to about 40 wt% sodium cocoamphoacetate on an actives basis.

[0208] In some embodiments, the metal species is a d-block metal species, preferably a platinum group species; the polymer backbone of the functionalised polymer is a cationic polymer when in aqueous solution, preferably a polyamine, a polyamide, or a combination thereof; the at least one covalently bound functional group is an aliphatic or aromatic hydrocarbon comprising 3 to 12 carbon atoms, or represented by formula (I), (II) or (III); the organic additive is a thioamide, a C1-C12 hydrocarbyl comprising at least two heteroatomcontaining groups, wherein the heteroatoms are N, O or S, or a N-heterocycle substituted by one or more N-containing groups; and the precipitant is selected from an anionic surfactant, an anionic polymer when in aqueous solution, and mixtures thereof.

[0209] In some embodiments, the target metal species is a platinum group species; the polymer backbone of the functionalised polymer is a polyamine, a polyamide, or a combination thereof; the at least one covalently bound functional group is an aliphatic or aromatic hydrocarbon comprising 3 to 12 carbon atoms, or represented by formula (I), (II) or (III); the organic additive is a thioamide, a C1-C12 hydrocarbyl comprising at least two heteroatom-containing groups selected from amine groups, imino groups, amide groups, sulfhydryls, carboxyl or carbonyl groups, a N-heterocycle substituted with one or more amino, imino, amide, imide, amidine, hydroazide, carbazide, cyano, oxime, or thioamide groups, or a combination thereof; and the precipitant is selected from an anionic surfactant, an anionic polymer when in aqueous solution, and mixtures thereof. Process for removing a target metal species

[0210] The second aspect of the present disclosure is a process for removing a target metal species from a solution as defined above. The target metal species is the metal species present in the aggregate of the first aspect. The solution comprises the target metal species, a solvent, and non-target metal species, wherein the non-target metal species is different from the target metal species.

[0211] By the term “different” is meant a different polarity and / or a different metal type, preferably the term “different” means metal type such that the metal species in solution have the same polarity, i.e. all cations or all anions. In other words, it is generally the case that the process separates a positively charged target metal species from or with non-target positively charged metal species, or alternatively, the process separates a negatively charged target metal species from or with non-target negatively charged metal species.

[0212] In various embodiments the solution to be treated comprises a plurality of metal species, and the plurality of metal species comprises the target metal species as defined above and at least one non-target metal species that is different from the target metal species, wherein the process is for removing at least the target metal species from the plurality of metal species in the solution. The process may also remove the at least one non-target metal species from the plurality of metal species in the solution.

[0213] The valency of the target metal species and the at least one non-target metal species need not be the same. The species may be monovalent or have a valency of two or more as defined above. However, a particular advantage of the process is that it is able to separate multiple charged species from a single solution. In some embodiments, therefore, the target metal species and the non-target metal species have the same valency and same polarity; such metal species may be metallic cations including monocations, dications, trications, tetracations, pentacations, hexacations, or the like.

[0214] The solution which is treated in the process of the present disclosure comprises the target metal species as defined above and a solvent, non-target metal species are optional. In preferred embodiments the solution comprises a target metal species, a non-target species, and a solvent. The solvent may be a single solvent or a mixture of different solvents. The metal species may further be at least partially dissolved in said solvent, although the present disclosure is not limited in this respect.

[0215] In various embodiments, the solvent comprises water and preferably, the solvent is aqueous. The term “aqueous” is used herein to refer to a solution containing at least 50 wt% water, based on the total weight of the solution. Other solvents may be present in addition to water, for instance one or more organic solvents.

[0216] When the solvent comprises one or more organic solvents, the organic solvent may be a polar organic solvent, for instance a polar protic solvent such as an alcohol or a carboxylic acid, a polar aprotic solvent such as acetonitrile, acetone, tetrahydrofuran (THF), or dimethyl sulfoxide (DMSO), an apolar organic solvent, for instance a hydrocarbon solvent such as pentane, hexane, toluene, or benzene, or a combination thereof. When the solvent comprises one or more organic solvents, the organic solvent is typically present at no more than about 20 wt% of the total solution, preferably no more than about 15 wt% of the total solution. For example, an aqueous solvent comprising no more than about 10 wt% of organic solvent may be used.

[0217] The metal species may be at least partially dissolved in the solvent; the metal species and solvent being defined above. The metal species may, for instance, be at least partially dissolved in the solvent prior to the start of the process of the present disclosure. In this respect, the metal species-containing solution may be a natural resource such as a river, lake or sea, and / or may comprise wastewater from an agricultural or industrial process. Alternatively, the solution may be an industrial effluent or a process stream. In various embodiments, the solution may be from an electronic plating process, e.g. the electronic plating bath. In various embodiments, the solution may be a waste stream produced during an industrial process, e.g. in the manufacture of catalysts or the like, or it may be a mixed metal aqueous waste stream produced during the preparation of an organic (e.g. pharmaceutical) product. Pharmaceutical processes use a variety of precious metal-bearing catalysts in the manufacture of drugs and other products. For example, palladium is widely used to facilitate cross-couplings, rhodium is used in hydroformylation reactions, and platinum is used to perform asymmetric hydrogenations.

[0218] In addition to the metal species and the solvent, the solution may comprise one or more further components. Such components are not limited because they depend on the source of the solution to be treated. The presence of one or more further components does not alter the beneficial results observed with the process of the present disclosure.

[0219] The process comprises treating the solution with a functionalised polymer and an organic additive to form a complex, and treating the solution with a precipitant. The functionalised polymer, organic additive, and precipitant are as defined above for the first aspect of the present disclosure. This definition is not repeated here for conciseness.

[0220] By the term “complex”, as used herein, is meant a molecular entity formed by the association of the functionalised polymer, organic additive, and metal species.

[0221] In some embodiments the complex is a solution phase species. In preferred embodiments the complex is a monophasic solution.

[0222] In various embodiments, the complex comprises a positively charged species formed from the functionalised polymer and a negatively charged species formed from the organic additive. In various embodiments, the complex comprises a negatively charged species formed from the functionalised polymer and a positively charged species formed from the organic additive. In various embodiments, the complex comprises a combination of positively charged species and negatively charged species from both the functionalised polymer and organic additive. The present disclosure is not limited in this respect. The complex further comprises the (target) metal species, bound with at least one group of the functionalised polymer. The (target) metal species may also be bound with at least one group of the organic additive. In various embodiments, the heteroatom-containing group on the organic additive is bound with the functionalised polymer and / or the metal species. The interaction is discussed above.

[0223] The functionalised polymer, the organic additive, and the precipitant may be added to the metal species-containing solution in any order, and one or more of the functionalised polymer, organic additive, and precipitant, may be pre-mixed prior to their addition to the metal species-containing solution. Thus, the process may comprise mixing the functionalised polymer with the organic additive, and treating the solution comprising the target metal species and the solvent with the mixture. Alternatively, the process may comprise the following steps in order: (i) treating the solution with the organic additive, and (ii) treating the solution with the functionalised polymer, or (i) treating the solution with the functionalised polymer, and (ii) treating the solution with the organic additive. In each of the above, it is preferable for the precipitant to be added after the polymer and / or the organic additive. In other embodiments, the solution may be treated with the polymer, organic additive and / or precipitant simultaneously.

[0224] In preferred embodiments, the functionalised polymer and organic additive are each in the liquid phase, such as an aqueous solution (the term “aqueous” being defined as above). The pH of the solution containing the functionalised polymer and the solution containing the organic additive groups is not critical to the present disclosure. Once added to the solution containing the target metal species, the pH of the resulting solution is similarly not critical to the present disclosure. The temperature may, however, by adjusted with optional agitation. This adjustment of temperature may be an increase in temperature, e.g. to at least about 50°C, and carried out prior to, during and / or after the addition of the precipitant. The precipitant may also be in the liquid phase, such as an aqueous solution.

[0225] The respective amount of functionalised polymer, organic additive and precipitant in the liquid phase is not limited and will depend upon the solution being treated, as well as the target metal species of the recovery process. Similarly, as the skilled person will appreciate, the relative amounts of the functionalised polymer, the organic additive, and the precipitant will depend upon the solution being treated as well as the metal species being removed, and the optimum amounts of polymer, organic additive and precipitant for that particular system. Such amounts will be readily determined by the person skilled in the art.

[0226] In some embodiments the amount of organic additive may be set relative to the amount of the target or non-target metal species. The molar concentration of the organic additive may, for instance, be at least equal to the molar concentration of target / non-target metal species in the solution. It could for instance be at least twice the molar concentration of the target / non-target metal species in the solution or even at least fifteen times the molar concentration of the target / non-target metal species in the solution. For instance, the ratio of the molar concentration of the organic additive to the molar concentration of the (target / non-target) metal species in solution may be from about 2:1 to about 40:1.

[0227] In some embodiments, the amount of organic additive may be set relative to the amount of a target metal species. The molar concentration of the organic additive may, for instance, be at least equal to the molar concentration of target metal species in the solution. It could for instance be at least twice the molar concentration of the target metal species in the solution or even at least fifteen times the molar concentration of the target metal species in the solution. For instance, the ratio of the molar concentration of the organic additive to the molar concentration of the target metal species in solution may be from about 2:1 to about 40:1.

[0228] In various embodiments, the amount of functionalised polymer may be set relative to the total amount of target and non-target metal species in solution. The molar ratio of the functionalised polymer to the target and non-target metal species may, for example, be about 1:10 to about 10:1. Given that the molar ratio depends on the degree of functionalisation, in other embodiments, the amount of functionalised polymer may be set relative to the total amount of target and non-target metal species in solution by a mass ratio. The mass ratio of the functionalised polymer to the sum of the target and non-target metal species in solution (the meaning of “target and non-target metal species in solution” above) may be from about 1:25 to about 10:1.

[0229] In various embodiments, the amount of functionalised polymer may be set relative to the amount of the target metal species. The molar ratio of the functionalised polymer to the target metal species may, for example, be greater than 1:10. In various embodiments, the molar ratio of the functionalised polymer to the target metal species may be from about 1:10 to about 10:1. Given that the molar ratio depends on the degree of functionalisation, in other embodiments, the amount of functionalised polymer may be set relative to the amount of target metal species in solution by a mass ratio. The mass ratio of the functionalised polymer to the target metal species in solution may be from about 1:10 to about 10:1.

[0230] The ratio of the molar concentration of the functionalised polymer to the molar concentration of the precipitant in the solution may be vary from case to case and may be any suitable ratio. Often however, the ratio of the molar concentration of the functionalised polymer to the molar concentration of the precipitant in the solution is from about 1:10 to about 10:1. A mass ratio of functionalised polymer to precipitant may alternatively be used; the mass ratio of functionalised polymer to precipitant may be from about 1:10 to about 10:1. Separation of the Complex

[0231] In various embodiments, the process further comprises the step of separating the complex from the solution. The complex is as defined herein. Separation of the complex from the solution may be carried out using any suitable technique known in the art. For example, a separation method based on real or artificial gravity, adsorption, decantation, elutriation, filtration, magnetic separation, sedimentation, centrifugation, sieving, or a combination thereof.

[0232] Absorption is a technique that is applied by introducing a new phase to absorb one or more components from the mixture that is encountered from the other phase; it can be physical absorption or chemical absorption. Adsorption is the adhesion of particles (e.g. particles in the complex, the target metal species, the functionalised polymer, or the precipitant) in solution to a surface, an example is adsorption onto carbon and flotation as defined below. Decantation is a process for the separation of mixtures, for example, by removing one or more liquid layers. Elutriation is a process for separating particles based on their size, shape and / or density. The process typically uses a stream of gas or liquid flowing in a direction usually opposite to the direction of sedimentation. Filtration is a process of separating solids from liquid using a medium that allows liquids to pass through it, but prevents solids of a certain size from passing through it. Magnetic separation is a process of using a magnetic force to remove a magnetically susceptible material. Sedimentation refers to the tendency for particles in suspension to settle out of a liquid. Centrifugation is a technique that uses centrifugal forces (using a centrifuge) and applies the principle of sedimentation by using the difference in density, shape and size to separate components from mixtures. Sieving is a process for separating solids from liquids using a sieve, i.e. a mesh or net capable of effectively trapping solid particles.

[0233] Generally, separating the complex from the solution depends on how the complex is present in the solution, i.e. as a suspension or other type of dispersion, and its particle size. In various embodiments, separating the complex from the solution comprises filtration, sedimentation, flotation, or a combination thereof. Filtration and sedimentation are defined above. Flotation is a process in which solids in suspension are recovered by their attachment to gas, usually air bubbles.

[0234] The step of separating the complex from the solution may comprise passing the solution through a filter, wherein the pore size of the filter is smaller than the size of the precipitate. The pore size may, for instance, be larger than the size of the target metal species. Thus, typically, the precipitate will not be able to pass through the filter whereas any metal species that are not part of a precipitate will be able to pass through the filter. As used herein, the pore size is the average diameter of the pore. If, for example, the pore is not spherical, the diameter of an individual pore is the diameter of a circle having the same area as the pore. The step of separating the complex from the solution may comprise passing the solution through a filter, wherein the filter has an average pore size of from 5 pm to 100 pm. Recovery of the Metal Species

[0235] In various embodiments the process further comprises the step of removing the target metal species from a composition comprising the complex. The composition comprises the aggregate of the present disclosure, where the target metal species is bound to at least one or more covalently bound groups of the polymer. The target metal species may be further bound to the precipitant. Thus, the process of removing the target metal species from said composition comprises removing the target metal species from the aggregate. A representative aggregate is shown in Figure 5.

[0236] In the process of the present disclosure, removing the target metal species from the composition may comprise forming a salt of the target metal species, or the precipitates can be incinerated the target metal species recovered as concentrated metal oxides. As the skilled person will appreciate, a salt is an ionic compound that may be formed when a positively charged species reacts with a negatively charged species to form an electrically neutral product. Typically, a salt is produced by the neutralization reaction between an acid and a base. Thus, the formation of a salt may require the pH of a solution to be adjusted (i.e. increased or decreased) to produce the desired result. Further, for the target metal species to form a neutral species, the salt formation typically requires the presence of a suitable counter ion, e.g. when the metal species is a positively charged species the counter ion will be a negatively charged counter ion and when the metal species is a negatively charged species the counter ion will be a positively charged counter ion. The counter ion may be found in the solution or may be added to the solution as part of the process of salt formation.

[0237] Thus, forming a dissolved salt of the target metal species optionally comprises adjusting the pH. When the target metal species is a positively charged species, adjusting the pH comprises treating the composition with an acidic solution. Thus, adjusting the pH often comprises reducing the pH, preferably reducing the pH to a pH of less than or equal to about 5. As the skilled person will appreciate, the adjusted pH depends upon the metal species present. The acid may for instance be selected from an inorganic acid, a sulfonic acid, a carboxylic acid and a halogenated carboxylic acid, or a combination thereof. The acid may, for instance, comprise an inorganic acid such as sulphuric acid (H2SO4). The sulphuric acid may, for instance, be a solution of sulphuric acid having a pH of approximately 1.

[0238] Alternatively, in the process of the present disclosure, removing the target metal species from the composition may comprise treating the composition with an amine solution. In other embodiments, the target metal species are negatively charged species and adjusting the pH comprises treating the composition with an alkaline solution. Thus, the process may comprise treating the composition with a base. Suitable bases include hydroxides such as sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH4OH), calcium hydroxide (Ca(OH)2), magnesium hydroxide (Mg(OH)2), barium hydroxide (Ba(OH)2), aluminium hydroxide (AI(OH)s), iron (ii) hydroxide (Fe(OH)2), iron (iii) hydroxide (Fe(OH)a), zinc hydroxide (Zn(OH)2) and lithium hydroxide (LiOH). The base may, for example, be sodium hydroxide or potassium hydroxide.

[0239] Typically, the process further comprises separating the salt of the target metal species from the functionalised polymer, organic additive and precipitant. The step of separating the salt from the functionalised polymer, organic additive and the precipitant may comprise a process of separation selected from combustion, adsorption, decantation, elutriation, filtration, magnetic separation, sedimentation and sieving, or a combination thereof. The process of separation may, for instance, be filtration or sedimentation, or a combination thereof. In some embodiments a concentrated salt is formed, followed by filtration / settling to separate this from the remaining polymer-additive-precipitant solid. In other embodiments a precipitated salt is formed, followed by filtration / settling to separate this from the solution of remaining polymer-additive-precipitant. Thus, preferably, separating the salt from the polymer, additive and precipitant comprises filtration, optionally wherein separating the salt from the polymer, additive and precipitant comprises filtering a composition comprising (i) a solution of the salt of the target metal species, and (ii) a precipitate comprising the polymer, organic additive and / or the precipitant, or (i) a solution of the polymer, organic additive and / or precipitant, and (ii) a precipitate comprising the salt of the target metal species. Filtering the composition may for example comprise using a filter having an average pore size of from 5 pm to 100 pm.

[0240] Removing the target metal species from the composition may comprise heating the composition and recovery of the target metal species in the form of an oxide comprising the target metal species. Typically, heating the composition comprises incineration of the composition. Typically, the heating also causes sublimation of the resulting metal oxide. The target metal species is typically then recovered in the form of a solid oxide comprising the target metal species.

[0241] After the step of removing the target metal species from the composition, the process of the present disclosure may further comprise recovering the polymer, organic additive and / or the precipitant. Typically, recovering the polymer, organic additive, and / or the precipitant comprises adjusting the pH of a composition comprising the polymer, organic additive, and precipitant.

[0242] In some embodiments, the target metal species are positively charged species, and the step of recovering the polymer, organic additive and / or the precipitant comprises treating the composition comprising the polymer, organic additive and / or the precipitant with a base or an alkaline solution. Thus, the step of recovering the polymer, organic additive and / or the precipitant comprises increasing the pH. Suitable bases for increasing the pH of the solution are outlined above.

[0243] In some embodiments, the target metal species are negatively charged species, and the step of recovering the polymer, organic additive and / or the precipitant comprises treating the composition comprising the polymer, organic additive and / or the precipitant with an acid, for instance with an acidic solution. The step of recovering the polymer, organic additive and / or the precipitant may, therefore, comprise decreasing the pH of the solution. The acid may comprise an inorganic acid (for instance sulfuric acid), a sulfonic acid, a carboxylic acid or a halogenated carboxylic acid.

[0244] After the step of recovering the polymer, organic additive and / or the precipitant, the recovered polymer, organic additive and / or the precipitant may, for instance, be used in another process, i.e. the recovered polymer, organic additive and / or the precipitant may be recycled. In one embodiment, the process of the present disclosure comprises re-using the recovered polymer, organic additive and / or the precipitant in a further cycle of the process of the disclosure. The further cycle of the process may be a process as further defined anywhere herein. Uses

[0245] A further aspect of the present disclosure is the use of a functionalised polymer, an organic additive, and a precipitant, to remove a target metal species from a solution. The solution comprises the target metal species and a solvent as defined herein. The solution may further comprise non-target metal species that are different from the target metal species. The functionalised polymer, organic additive, precipitant, and target and non-target metal species being as defined herein for the first and second aspects of the present disclosure.

[0246] A further aspect of the present disclosure is the use of an organic additive to modify the binding affinity of a metal species in solution for a functionalised polymer, wherein the solution comprises the metal species and a solvent, and wherein the binding affinity of the metal species for the functionalised polymer is modified relative to without the organic additive. A comparison can, for example, be made between (1) the binding affinity of a metal species in solution for a functionalised polymer, and (2) the binding affinity of the same metal species in the same solution for the same functionalised polymer, in the presence of the organic additive. The organic additive will either increase or decrease the binding affinity of the metal species in solution for the functionalised polymer.

[0247] The measurement of binding affinity is known in the art; it is typically carried out using spectroscopic techniques such as NMR and UV-Vis depending on the species involved. The choice of a suitable method is within the common general knowledge of the person skilled in the art. Example methods are discussed in Berry et al., React. Chern. Eng., 2022, 7, 2009-2024, and Gamov et al., Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2019, 206, 160-164.

[0248] In this aspect of the present disclosure, the functionalised polymer and the organic additive are solution phase species. This represents an advantage over ion-exchange resins which typically involve solid phase species in order to recover one or more metal species from a solution. As explained above, the performance of resin-based ion exchange technology is limited by a relatively slow kinetic and hydraulic performance due to the heterogeneous solidliquid interactions that are required for its operation, and by the corresponding complexity of fixed-bed process operation. Such limitations are not present in the process of the present disclosure.

[0249] As a further advantage over resin-based ion-exchange technology, the functionalised polymer and the organic additive may be monophasic. The term “monophasic” means having a single phase.

[0250] The features disclosed above for the first and second aspects of the present disclosure apply equally to the uses of the present disclosure and vice versa.

[0251] The aspects of the present disclosure will be further described in the following Examples. EXAMPLES

[0252] In the exemplified process of the present disclosure, an aqueous solution containing a nickel species, a palladium species and a rhodium species is treated with a 10% w / w aqueous solution of functionalised polymer (e.g. a reaction product of a polyamine and one or more functional groups) and a 10% w / w aqueous solution of organic additive in order to recover the palladium and rhodium species. The palladium and rhodium cations were the target metal species, and the nickel cation was the non-target metal species.

[0253] Following a complexation period, for example from 30 minutes to 6 hours at 40 to 70°C, a precipitant (here a surfactant) was added to the solution. The solid aggregate comprising the functionalised polymer-organic additive-metal species-precipitant was subsequently gathered via recirculating filtration. The recovery of each metal species was quantified by comparing the initial concentration with the liquor concentration. Such concentrations were measured by ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy), as is known in the art.

[0254] With the unfunctionalised polymer both recoveries and selectivity of target and nontarget metal species remained moderate. The functionalised polymer and organic additive was found, however, to enhance the recovery of the platinum group species over nickel. Specifically, the organic additive modified the binding affinity of the functionalised polymer for the target metal species.

[0255] Using the above-described exemplified process, a number of experiments were designed as follows: 1. Comparison of Unfunctionalized Polymers with Functionalized Polymers: This experiment aimed to compare the efficacy of unfunctionalized polymers against functionalized polymers in selective metal recovery processes. The focus was on assessing the selectivity and efficiency of metal recovery when using functionalized polymers compared to their unfunctionalized counterparts in combination with a representative organic additive. 2. Effect of Organic Additives in Selective Recovery of Target Metal Using Functionalized Polymer: This experiment investigated the effect of organic additives on the selective recovery of target metals when employing functionalized polymers. Different organic additives were tested with representative functionalised polymers. 3. Effect of Organic Co-additives in Selective Recovery of Target Metal Using Functionalized Polymer: Here, the experiment explored the synergistic effects of organic co-additives in the selective recovery of target metals with functionalized polymers. Various combinations of organic co-additives were studied to evaluate their role in enhancing the effectiveness and specificity of metal recovery processes. 4. Influence of Precipitants on Metal Recovery Using Functionalized Polymer: This experiment investigated the impact of various precipitants on the selective recovery of target metals using functionalized polymers in the presence of organic additives. Different precipitants were evaluated to understand their role in enhancing metal recovery efficiency and selectivity. Results and Discussion

[0256] To address all the above-mentioned goals, two synthetic solutions containing various metals were prepared. In all cases, experiments were conducted at a 5 mL scale in glass vials, which were magnetically agitated to ensure homogeneity. The mass ratio of the functionalised polymer to the target metals in solution was set at from 0.6:1 to 4.5:1.

[0257] The functionalised polymer-precipitant (here surfactant, specifically SDS) mass ratio was fixed at 1:5.

[0258] Unless otherwise specified, all organic additives were utilized as a 10%w / w aqueous solution, and the mass ratio of the additive to one of the target metals was maintained at 20:1.

[0259] The test solutions utilized were synthetic solutions, and all pH adjustments were made using 10%w / w hydrochloric acid and 10%w / w sodium hydroxide to maintain desired pH levels.

[0260] The list of polymers, organic additives and precipitants used can be found below. Synthetic solution containing Rh, Pd and Ni

[0261] To mimic real-world scenarios and assess the effectiveness of the metal recovery process across a diverse range of metal species, the initial synthetic solution was formulated using a mixture of precious metal salts and a base metal salt. Nickel, at a concentration of 2000 ppm, was selected as the representative base metal. Simultaneously, palladium and rhodium, each at concentrations of 100 ppm, were included as the precious group metals (PGMs) in the solution. In this experiment, the base metal was regarded as contaminant or non-target metal, while palladium and rhodium were identified as the target metals, emphasizing the selective recovery aspect of the process.

[0262] In the first experiment, the influence of polymer functionalization was investigated in conjunction with the introduction of organic additives on the overall recovery and selectivity of metals from the solution (Table 1). In each case, a 10% w / w solution of thiourea was chosen as the representative organic additive, with a mass ratio of 20:1 relative to Rh. The mass ratio of polymer to total metal (sum of target metal and non-target metal) remained constant across all experiments as 0.2:1. Table 1. Impact of polymer functionalization and organic additive in metal recovery process Entry § Polymer Rh %recovery Ni %recovery Pd % recovery 1 § PEI 16 8 35 2 1 2-PPEI 80 3 96 3 Bu-PEI 80 7 90 4 GCMA 76 1 97

[0263] With unfunctionalized PEI and the organic additive, both recoveries and selectivity remained moderate (Table 1, entry 1). However, with functionalized polymers and the range of organic additives tested, a notable enhancement in the recovery of precious group metals was observed (Table 1, entries 2-4). The functional group on the polymer exerted a significant influence on both the recoveries and selectivity when combined with the organic additives.

[0264] Next, the objective was to investigate the influence of organic additive structure and functionality on the selectivity and efficacy of the process. To accomplish this, tests were conducted using a variety of organic additives in combination with the functionalized polymers. The results obtained for each functionalized polymer are presented in separate sections below. Various organic additives in combination with GCMA as the functionalized polymer

[0265] Initially, the efficacy of PEI was compared with a functionalized variant known as GCMA in the selective metal recovery process. Table 2. Effect of additives on recovery of PGMs using GCMA § Entry Polymer Organic additive Rh %recovery Ni %recovery Pd %recovery § 1 PEI none 46 10 70 § § 2 GCMA none 100 100 76 i ['3 GCMA 2-aminopyridine 24 ~12 85 | 4 GCMA TGA 37 1 48 |~5 GCMA Thiourea 76 1 97 § 6 GCMA Glycine 5 1 14 j h GCMA Glycine+ 2- 9 "5 24 | aminopyridine

[0266] When PEI was used, the recovery percentages of the precious group metals were moderate, with poor recovery of nickel from the solution. However, upon utilizing GCMA, significant enhancements in the recovery of all three metals were observed albeit with low selectivity (Table 2, entries 1-2). Upon the introduction of organic additives, an enhanced selectivity was observed in recovering PGMs over nickel (Table 2, entries 3-7). In each instance, a 10% w / w aqueous solution of corresponding organic additive was used, with a mass ratio of 20:1 relative to Rh. The mass ratio of polymer to total metal (sum of target metal and non-target metal) remained constant across all experiments as 0.2:1.

[0267] The nature of the organic additive impacted the selectivity of the recovery process. For example, when 2-aminopyridine was used as the organic additive, significant changes in metal recovery were observed (Table 2, entry 3). While nickel recovery dropped drastically, palladium recovery increased to 85%, indicating how an organic additive could enhance the selectivity of the process. It can also be seen that rhodium recovery decreased by almost 20%, suggesting that the introduction of 2-aminopyridine retains rhodium in the solution. This result suggests that an organic additive could potentially serve to keep a contaminant metal in the solution while enhancing the recovery of a target metal. In the case of 2-aminopyridine, it is believed that it either forms a complex with rhodium which has limited binding affinity to the functionalised polymer, or does not interact with rhodium at all. This is in contrast to palladium where the complex formed appears to interact effectively with the functionalised polymer.

[0268] Upon the use of TGA (thioglycolic acid), nearly all the nickel remained in the solution, while both palladium and rhodium were moderately recovered without a preference for one over the other (Table 2, entry 4). The selective action of TGA highlights its potential efficacy in metal recovery processes, particularly for isolating precious metals while leaving other base metals, such as nickel, in solution.

[0269] Similar to TGA, thiourea also had the effect of retaining nickel in the solution (Table 2, entry 5). However, unlike TGA, thiourea demonstrated a significant enhancement in the recovery of both palladium and rhodium. Both palladium and rhodium could be recovered excellently in the presence of thiourea as an organic additive. This indicates that thiourea has a selective effect on the recovery of PGMs, promoting their efficient extraction while minimizing the recovery of nickel.

[0270] As shown, certain organic additives possess the capability to retain all metals in the solution to some extent while demonstrating selectivity in their action. Glycine exemplifies such an additive (Table 2, entry 6). Upon its introduction to the test solution containing Pd, Rh, and Ni, significant reductions in all metal recoveries were observed. Despite the overall decrease in recovery percentages, more PGMs were captured. This suggests that glycine selectively enhances the capture of PGMs while maintaining the presence of all metals in the solution to some degree. In this context, the introduction of a co-additive such as 2-aminopyridine leads to slight enhancements in the recoveries of all metals while preserving the selectivity observed with glycine alone (Table 2, entry 7). This indicates that 2-aminopyridine complements the action of glycine, potentially improving the efficiency of metal recovery processes without compromising selectivity.

[0271] The binding affinity of heteroatom-containing groups for metal species is known in the art. S-containing groups are, for example, known to have a high binding affinity for precious metals. Hence, the skilled person is readily able to identify an organic additive depending on the target metal species and / or functionalised polymer. This is supported by the extensive experiments presented herein. Various organic additives in combination with Bu-PEI as the functionalized polymer

[0272] In another experiment utilizing the same synthetic solution as above but in the presence of another functionalized PEI variant known as Bu-PEI, organic additives were demonstrated to be effective in not only enhancing the selectivity but also the efficacy of the metal flocculation process. Table 3. Effect of organic additives on recovery of PGMs using Bu-PEI § Entry 1 Polymer Bu-PEI Organic additive none Rh % recovery 9 Ni %recovery 6 Pd %recovery 28 § 2 Bu-PEI 2-aminopyridine 31 19 84 § 3 Bu-PEI TGA 64 4 55 4 Bu-PEI Thiourea 79 7 91 5 Bu-PEI Glycine 10 4 32 § 6 Bu-PEI Glycine+ 2- aminopyridine 0.1 4 27

[0273] Initially, in the absence of any organic additive, the recoveries proved to be low (Table 3, entry 1). However, upon the introduction of additives such as thiourea, 2-aminopyridine, and TGA, an enhanced recovery and selectivity were observed (Table 3, entries 2-4).

[0274] In each instance, a 10% w / w aqueous solution of corresponding organic additive was used, with a mass ratio of 20:1 relative to Rh. The mass ratio of polymer to total metal (sum of target metal and non-target metal) remained constant across all experiments as 0.2:1. While all three organic additives showed improved selectivity for PGMs by retaining base metal in the solution, thiourea emerged as the most effective in terms of total metal recovery. Of these additives, both thiourea and TGA did not display significant selectivity for palladium over rhodium. However, 2-aminopyridine exhibited a higher degree of selectivity towards palladium compared to rhodium. This is same result as seen above with 2-aminopyridine.

[0275] These findings further demonstrate that the organic additive can be tailored to optimize the recovery process based on the specific target metals involved. For example, sulfur-containing groups are known to bind effectively to both palladium and rhodium.

[0276] When glycine was utilized as an organic additive, neither the recoveries nor the selectivity was improved compared to the experiments conducted in the absence of organic additives (Table 3, entries 1&5). An explanation for this result is the acidic environment arising from the metal species in solution. Protonation of the amino group on the residue may, for instance, be reducing the level of interaction between the glycine additive and the metal species in solution. Alternatively, the glycine additive may be forming a complex with the metal species which is then not interacting with the functionalised polymer. It can be seen that the introduction of a co-additive such as 2-aminopyridine with glycine led to a significantly enhanced selectivity between rhodium and palladium. This combination effectively retained rhodium in the solution, resulting in the selective recovery of palladium (Table 3, entry 6).

[0277] In summary, based on the proposed mechanism, the results seen with glycine as the organic additive indicate that either the additive and target metal are not interacting to form a 'complex' or that the formed 'complex' is not interacting with the functionalised polymer or incorporated into the aggregate. A 'complex' may not form due to incompatibility of the target metal and the additive, such as the target metal having an unfavourable oxidation state or the additive existing predominantly in an ionised or tautomeric form. The term “unfavourable” is relative to the organic additive or target metal species. For example, whilst a M(2+) ion may not be interacting with the organic additive, the corresponding M(3+) ion will do so.

[0278] If the 'complex' is not formed then this could easily be resolved via the addition of a coadditive (as demonstrated above). The skilled person may also change the solution conditions of the process, such as the pH, or redox potential of the solution containing the target metal species. For example, the skilled person could identify the formation of a 'complex' via UV-Vis spectroscopy or NMR analysis and may make solution adjustments based on known techniques. As is known in the art, redox potential may be controlled via the addition of oxidant e.g. H2O2 or addition of a reductant e.g. hydrazine. Redox potential is monitored vs. SHE with an electrode. pH may be controlled via the addition of an acidic or basic solution; example solutions are noted above.

[0279] If the 'complex' is not interacting with the functionalised polymer then this again could be resolved via a change in solution conditions, providing the complex is not affected. In most cases replacement of the functionalised polymer or introduction of a co-additive is more straightforward typically through selecting a functionalised polymer with a different complexing group (for target metal affinity) or a different hydrophobic / hydrophilic character. Changing other aspects of the functionalised polymer, such as the backbone monomer may also prove beneficial to the process. Various organic additives in combination with 2-PPEI as the functionalized polymer

[0280] When 2-PPEI was employed as the functionalized polymer, it demonstrated selectivity towards palladium compared to rhodium and nickel in the absence of any organic additive (Table 4, entry 1). However, the introduction of organic additives such as thiourea and TGA resulted in enhanced recovery of both PGMs while maintaining most of the nickel in the solution (Table 4, entries 2-3). Without wishing to be bound by theory, this enhancement in selectivity is believed to be the result of an interaction between the thiourea / TGA and Rh / Pd which enhances their binding affinity with the functionalised polymer. Table 4. Effect of additives on recovery of PGMs using 2-PPEI ; Entry Polymer Organic additive Rh %recovery Ni %recovery Pd %recovery ; 1 2-PPEI none ; 8 3.5 44 ; 2 2-PPEI Thiourea ; 80 3 96 3 2-PPEI TGA 61 2 52 H 2-ppei 2-aminopyridine ] 8 3 45 ; 5 2-PPEI Glycine ; 7 1.7 42

[0281] In a similar manner to the above experiments with Bu-PEI, 2-aminopyridine and glycine were not as effective as thiourea or TGA. The same rationale applies in terms of the mechanism behind the target metal recovery and the manner in which these additives could be used to effect selective metal recovery.

[0282] In conclusion, the organic additive in combination with functionalized polymer, results in an ability to tailor the selectivity and efficacy of the metal recovery process. The synergistic effects observed when organic additives are combined as co-additives further highlight the potential for optimizing both recovery and selectivity towards the target metal. Various precipitants in combination with 2-PPEI as the functionalized polymer

[0283] In another series of experiments conducted with the same synthetic solution as above and employing 2-PPEI as the representative functionalized polymer and 2-aminopyridine as the representative organic additive, the influence of various precipitants on the effectiveness of the metal flocculation process was investigated. The metal %recovery values are for the filtrate as a whole; the aggregates were not analysed for their component make-up. Table 5. Effect of precipitant on recovery of PGMs using 2-PPEI ; Entry Polymer Precipitant ; Rh [ %recovery [ Ni %recovery Pd %recovery ; 1 2-PPEI SDS ; 8 ; 3 45 ; 2 2-PPEI SDBS ; 32 25 95 P 2-PPEI| Ammonium sulfate lauryl [ 0 ] 8 ~19 4 2-PPEI PSSA [ 66 70 42 ; 5 2-PPEI PAA 70 § 45 57 §

[0284] Initially, when SDS was employed as the precipitant, the process exhibited greater selectivity towards palladium (Table 5, entry 1). Subsequently, utilizing SDBS, which is slightly more hydrophobic than SDS, led to an improved recovery of both PGMs and nickel, while maintaining a high level of selectivity towards palladium (Table 5, entry 2).

[0285] To study the impact of counter ions on the precipitant, ammonium dodecyl sulphate was compared with its sodium variant. Upon changing the counter ion to ammonium, recovery of PGMs dropped drastically while nickel recovery improved slightly (Table 5, entries 1 &3).

[0286] Upon utilizing another polymer, polystyrene sulfonic acid, as a precipitant, an enhanced recovery of both rhodium and nickel was observed while palladium recovery remained consistent (Table 5, entry 4).

[0287] Alternatively, when polyallylamine was used as the precipitant, there was an enhancement in the recovery of both PGMs and nickel with higher selectivity towards PGMs (Table 5, entry 5).

[0288] In summary, the precipitants can play a role in the claimed metal recovery processes. Both the structure of the precipitant and the nature of the counter ion proved to be of interest, especially in the case of charged precipitants. Furthermore, the use of polymers as precipitants is shown to be viable. Table 6. Polymers Polymer Name Approximate structure of Polymer Backbone Functional Group Class PEI w .ss, vwwwwwwwwwwwwwwwwwww Unfunctionalised •••• •••■• . . x _ j: 2-PPEI — s’"''"' I-’’ X A — Functionalised >•< Bu-PEI ss- .SV, Functionalised --.s. x ••• ? \X A ;; -v. s..: GCMA '■ •. x'’ X x-''''' * > Functionalised Ben-PEI [' 1 i i; 'NX X i : Functionalised 4-PPEI f 1 Functionalised Table 7. Organic additive structures Organic additive Structure 2-Aminopyridine <v Thioglycolic acid Thiourea Glycine Picolinic acid Nicotinic acid M'v* 'O*^ 8-Hydroxyquinoline O^- Table 8. Precipitant structures Precipitant Structure Sodium dodecyl Sulfate (SDS) X £ Na+ 6' °' Dodecylbenzene sulfonic acid sodium salt (SDBS) Ammonium lauryl sulfate Poly(styrene sulfonic acid) (PSSA) Polyallyl amine Na* O S, 0* i A s / VW J I r 's n

[0289] The various embodiments described herein are presented only to assist in understanding and teaching the claimed features. These embodiments are provided as a representative sample of embodiments only, and are not exhaustive and / or exclusive. It is to be understood that advantages, embodiments, examples, functions, features, structures, and / or other aspects described herein are not to be considered limitations on the scope of the invention as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope of the claimed invention. Various embodiments of the invention may suitably comprise, consist of, or consist essentially of, appropriate combinations of the disclosed elements, components, features, parts, steps, means, etc., other than those specifically described herein. In addition, this disclosure may include other inventions not presently claimed, but which may be claimed in future.

[0290] Further embodiments are defined in the following numbered clauses: 1. A product in the form of an aggregate comprising: a. a functionalised polymer which is a polymer with at least one covalently bound functional group; b. an organic additive which is a hydrocarbyl substituted by at least one heteroatom-containing group, and wherein the organic additive comprises at least one group that binds a metal species; c. a metal species; and d. a precipitant, wherein the precipitant comprises at least one hydrophilic moiety and at least one hydrophobic moiety, and at least one group that binds the functionalised polymer and / or the metal species; wherein the functionalised polymer comprises at least one moiety that binds the metal species. 2. The product of clause 1, wherein the product is in the form of a solid. 3. The product of clause 1 or clause 2, wherein the organic additive comprises at least one group that binds the metal species and / or the covalently bound functional group of the polymer. 4. The product of any preceding clause, wherein the functionalised polymer is electrostatically bound to the metal species. 5. The product of any preceding clause, wherein the functionalised polymer is bound to the organic additive, and the organic additive is bound to the metal species, and / or the functionalised polymer is bound to the metal species, and the organic additive is bound to the functionalised polymer and / or the metal species. 6. The product of any preceding clause, wherein the backbone of the functionalised polymer is a polyelectrolytic polymer when in aqueous solution. 7. The product of any preceding clause, wherein one or more of the covalently bound functional groups of the polymer is a moiety that binds the metal species. 8. The product of any preceding clause, wherein the functionalised polymer comprises at least one moiety that binds the organic additive. 9. The product of any preceding clause, wherein the at least one covalently bound functional group of the polymer is an aliphatic or aromatic hydrocarbon. 10. The product of clause 9, wherein the aliphatic or aromatic hydrocarbon comprises 3 to 12 carbon atoms. 11. The product of any of clauses 1 to 10, wherein the at least one covalently bound functional group of the polymer comprises at least one heteroatom. 12. The product of clause 11, wherein the heteroatom is selected from N, O, P, S, and combinations thereof. 13. The product of clause 12, wherein the heteroatom is selected from N, O, S, and combinations thereof. 14. The product of clause 13, wherein the heteroatom is selected from N, S, and combinations thereof, or N, 0, and combinations thereof. 15. The product of any of clauses 1 to 12, wherein the at least one covalently bound functional group of the polymer comprises one or more hydroxyl groups, ether groups, carboxyl groups, carbonyl groups, sulfonic acid groups, sulfinic acid groups, sulfhydryl groups, sulfide groups, thioketone groups, thial groups, thioester groups, thioamide groups, phosphoric acid groups, phosphinic acid groups, phosphonic acid groups, cyano groups, amino groups, imino groups, imide groups, amide groups, amidine groups, oxime groups, hydrazide groups, carbazide groups, quaternary nitrogen groups, N-heterocycles, or a combination thereof. 16. The product of any of clauses 1 to 13, wherein the at least one covalently bound functional group of the polymer comprises one or more hydroxyl groups, ether groups, carboxyl groups, carbonyl groups, sulfonic acid groups, sulfinic acid groups, sulfhydryl groups, sulfide groups, thioketone groups, thial groups, thioester groups, thioamide groups, cyano groups, amino groups, imino groups, imide groups, amide groups, amidine groups, oxime groups, hydrazide groups, carbazide groups, quaternary nitrogen groups, N-heterocycles, or a combination thereof. 17. The product of any of clauses 1 to 14, wherein the at least one covalently bound functional group of the polymer comprises one or more sulfonic acid groups, sulfinic acid groups, sulfhydryl groups, sulfide groups, thioketone groups, thial groups, thioester groups, thioamide groups, cyano groups, amino groups, imino groups, imide groups, amide groups, amidine groups, oxime groups, hydrazide groups, carbazide groups, quaternary nitrogen groups, N-heterocycles, or a combination thereof, or one or more hydroxyl groups, ether groups, carboxyl groups, carbonyl groups, cyano groups, amino groups, imino groups, imide groups, amide groups, amidine groups, oxime groups, hydrazide groups, carbazide groups, quaternary nitrogen groups, N-heterocycles, or a combination thereof. 18. The product of clause 17, wherein the at least one covalently bound functional group of the polymer comprises a N-heterocycle. 19. The product of clause 17 or clause 18, wherein the at least one covalently bound functional group of the polymer is represented by formula (I) or (II): wherein Xi, X2, X3, X4, and X5 in formula (I) and Xi, X2, X3, and X4 in formula (II) are independently C or N, provided that at least one is N; wherein Ri and R2 are independently selected from -H, =0, -SRa, -0Ra, =S, =N, N(Ra)2, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -0Rb, -SRb, -N(Rb)2, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is 0 or S; wherein x is an integer from 1 to 4; wherein n is 0 or an integer from 1 to 8; and wherein m is 0 or an integer from 1 to 8. 20. The product of any of clauses 17 to 19, wherein the at least one covalently bound functional group of the polymer comprises a thioamide group, preferably a thiourea or a thiocarbamate. 21. The product of any of clauses 17 to 20, wherein the at least one covalently bound functional group of the polymer comprises an aliphatic hydrocarbon substituted by at least one S-containing group, N-containing group and / or O-containing group. 22. The product of clause 21, wherein the at least one covalently bound functional group of the polymer is represented by formula (III): wherein R3 and R4 are independently selected from -H, =0, -SRa, -0Ra, =S, =N, -N(Ra)2, -N(Rb)3+A’, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -N(Rb)3, -N(Rb)3+A', -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SC(O) NRbRb, -OC(S)NRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, or a combination thereof; wherein Xe is -0Rb, -SRb, -N(Rb)2, -N(Rb)3+A-, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SC(O) NRbRb, -OC(S)NRbRb, -SxC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, or a combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is 0 or S; wherein A is an anion; wherein x is an integer from 1 to 4; wherein n is 0 or an integer from 1 to 8; and wherein m is 0 or an integer from 1 to 8. 23. The product of any preceding clause, wherein the polymer backbone of the functionalised polymer is a cationic polymer when in aqueous solution. 24. The product of any preceding clause, wherein the polymer backbone of the functionalised polymer is a polyamine, a polyamide, or a combination thereof. 25. The product of any preceding clause, wherein the polymer backbone of the functionalised polymer comprises polyethyleneimine, polyvinylamine, polyallylamine, chitosan, polylysine, polyarginine, polyamide, polyacrylamide, or a combination thereof. 26. The product of any preceding clause, wherein the polymer backbone of the functionalised polymer comprises polyethyleneimine, polyvinylamine, polyallylamine, polyamide, polyacrylamide, or a combination thereof. 27. The product of any preceding clause, wherein the polymer backbone of the functionalised polymer is a polymer derived from aziridine. 28. The product of any of clauses 1 to 27, wherein the functionalised polymer is a reaction product of the polymer backbone and one or more of an aliphatic carboxylic acid, an epoxide, an episulfide, polyethylene glycol, polyvinyl alcohol, or polyamide. 29. The product of any preceding clause, wherein the polymer backbone of the functionalised polymer is an anionic polymer when in aqueous solution. 30. The product of any preceding clause, wherein the polymer backbone of the functionalised polymer is a carboxylate, sulfate, or sulfonate polymer. 31. The product of clause 30, wherein the polymer backbone of the functionalised polymer comprises polyacrylate, polymethacrylate, polymaleate, polysulfonate, or a combination thereof. 32. The product of any preceding clause, wherein the organic additive has a number average molecular weight of about 1000 Da or less, as measured by gel permeation chromatography with a polystyrene standard. 33. The product of any preceding clause, wherein the organic additive includes at least two heteroatom-containing groups. 34. The product of clause 33, wherein the at least two heteroatom-containing groups differ from each other by the heteroatom and / or coordination environment. 35. The product of clause 33 or clause 34, wherein the at least two heteroatom-containing groups are N-containing groups. 36. The product of clause 35, wherein the N-containing groups are selected from amino groups, imino groups, amide groups, imide groups, diazonium compounds, amidine groups, hydrazide groups, carbazide groups, cyano groups, oxime groups, thioamide groups, and N-heterocycles. 37. The product of clause 36, wherein the N-containing groups are a N-heterocycle, substituted by one or more amino, imino, amide, imide, amidine, hydroazide, carbazide, cyano, oxime, or thioamide groups, or a thioamide. 38. The product of clause 33 or clause 34, wherein the at least two heteroatom-containing groups are (i) a N-containing group and a S-containing group, or (ii) a S-containing group and an O-containing group. 39. The product of clause 38, wherein the N-containing group is selected amino groups, imino groups, amide groups, imide groups, diazonium compounds, amidine groups, hydrazide groups, carbazide groups, cyano groups, oxime groups, thioamide groups, and N-heterocycles; wherein the S-containing group is selected from sulfonic acid groups, sulfinic acid groups, thioketone groups, thial groups, thioester groups, thioamide groups, and sulfhydryl groups; and wherein the O-containing group is selected from hydroxyl groups, carboxyl groups, and carbonyl groups. 40. The product of clause 39, wherein the at least two heteroatom-containing groups are a N-containing group and a S-containing group, wherein the N-containing group is selected from amino groups, imino groups, amide groups, imide groups, cyano groups, and N-heterocycles, and wherein the S-containing group is selected from thioketones, thioesters, thioamides, and sulfhydryl groups. 41. The product of any preceding clause, wherein the organic additive includes at least three heteroatom-containing groups. 42. The product of clause 35, wherein the at least three heteroatom-containing groups are a N-containing group, a S-containing group and an O-containing group. 43. The product of clause 42, wherein the N-containing group is selected from amino groups, imino groups, amide groups, imide groups, diazonium compounds, amidine groups, hydrazide groups, carbazide groups, cyano groups, oxime groups, thioamide groups, and N-heterocycles; wherein the S-containing group is selected from sulfonic acid groups, sulfinic acid groups, thioketone groups, thial groups, thioester groups, thioamide groups, and sulfhydryl groups; and wherein the O-containing group is selected from hydroxyl groups, carboxyl groups, and carbonyl groups. 44. The product of clause 43, wherein the N-containing group is an amino group, an amide group, an imino group or a N-heterocycle, wherein the S-containing group is a thioamide group, and wherein the O-containing group is a carboxyl group. 45. The product of any preceding clause, wherein the at least one heteroatom-containing group of the organic additive is a group that binds a metal species. 46. The product of any preceding clause, wherein the at least one heteroatom-containing group of the organic additive is selected from a carboxyl group, a carbonyl group, a sulfonic acid group, a sulfinic acid group, a thioketone group, a thial group, a thioester group, a thioamide group, a sulfhydryl group, a phosphoric acid group, a phosphinic acid group, a phosphonic acid group, an amino group, an imino group, an amide group, an imide group, an amidine group, a N-heterocycle group, and a combination thereof. 47. The product of any preceding clause, wherein the at least one heteroatom-containing group of the organic additive is selected from a carboxyl group, a carbonyl group, a sulfonic acid group, a sulfinic acid group, a thioketone group, a thial group, a thioester group, a thioamide group, a sulfhydryl group, an amino group, an imino group, an amide group, a N-heterocycle group, and a combination thereof. 48. The product of any preceding clause, wherein the organic additive is a C1-C12 hydrocarbyl substituted by the at least one heteroatom-containing group. 49. The product of any preceding clause, wherein the organic additive is a C1-C12 hydrocarbyl substituted by at least two heteroatom-containing groups. 50. The product of any preceding clause wherein the organic additive is a thioamide or a C1-C12 hydrocarbyl substituted by a sulfhydryl group. 51. The product of any preceding clause, wherein the organic additive is a C1-C12 hydrocarbyl substituted by at least one amine group, imino group, amide group, carboxyl or carbonyl group. 52. The product of any preceding clause, wherein the metal species is selected from d-block metal species, preferably platinum group species. 53. The product of any preceding clause, wherein the metal of the metal species is selected from scandium, vanadium, chromium, manganese, cobalt, nickel, copper, yttrium, niobium, ruthenium, rhodium, silver, cadmium, tungsten, rhenium, osmium, iridium, platinum, gold, mercury, or a mixture thereof, preferably scandium, vanadium, chromium, manganese, yttrium, niobium, ruthenium, rhodium, silver, cadmium, tungsten, rhenium, osmium, iridium, platinum, gold, mercury, or a mixture thereof. 54. The product of any preceding clause, wherein the metal species comprises a metallic ion or a mixture thereof. 55. The product of any preceding clause, wherein the metal species comprises a metallic cation or a mixture thereof. 56. The product of any preceding clause, wherein the precipitant is a surfactant or a polymer which is anionic or cationic when in aqueous solution. 57. The product of any preceding clause, wherein the precipitant is selected from anionic surfactants, amphoteric surfactants, cationic surfactants, and mixtures thereof. 58. The product of any preceding clause, wherein the precipitant is selected from anionic surfactants, cationic surfactants, and mixtures thereof. 59. The product of any preceding clause, wherein the polymer backbone of the functionalised polymer is cationic when in aqueous solution and the precipitant is selected from an anionic surfactant, a polymer which is anionic in aqueous solution, and mixtures thereof. 60. The product of any preceding clause, wherein the precipitant is an anionic surfactant and the anionic surfactant comprises: an anionic functional group selected from a sulfate, sulfonate, phosphate, phosphonate, and carboxylate group; and an alkyl chain comprising from 5 to 20 carbon atoms. 61. The product of clause 60, wherein the anionic surfactant is a C5-C20 alkyl sulfate. 62. The product of any of clauses 1 to 58, wherein the polymer backbone of the functionalised polymer is anionic when in aqueous solution and the precipitant is selected from a cationic surfactant, a polymer which is cationic in aqueous solution, and mixtures thereof. 63. The product of clause 62, wherein the precipitant is a cationic surfactant, and the cationic surfactant comprises a cationic functional group comprising a quaternary nitrogen having the formula: (NR1R2R3R4)+, wherein R1, R2, R3 and R4 are independently selected from substituted or unsubstituted C1-C18 alkyl groups. 64. The product of any of clauses 1 to 61, wherein: the metal species is a d-block metal species, preferably a platinum group species; the polymer backbone of the functionalised polymer is a cationic polymer when in aqueous solution; the at least one covalently bound functional group is an aliphatic or aromatic hydrocarbon comprising 3 to 12 carbon atoms, or represented by formula (I), (II) or (HI); the organic additive is a thioamide, or a C1-C12 hydrocarbyl comprising at least two heteroatom-containing groups, wherein the heteroatoms are N, O or S; and the precipitant is selected from an anionic surfactant and mixtures thereof. 65. A process for removing a target metal species from a solution, wherein the solution comprises the target metal species, a solvent, and optionally non-target metal species, wherein the non-target metal species is different from the target metal species, which process comprises treating the solution with a functionalised polymer and an organic additive to form a complex, and treating the solution with a precipitant; wherein the organic additive is a hydrocarbyl group substituted by at least one heteroatom-containing group, and wherein the organic additive comprises at least one group that binds a metal species; wherein the functionalised polymer is a polymer with at least one covalently bound functional group, and at least one moiety that binds the target metal species; wherein the precipitant comprises at least one hydrophilic moiety and at least one hydrophobic moiety, and at least one group that binds the functionalised polymer and / or the target metal species. 66. The process of clause 65, wherein the functionalised polymer, organic additive and / or precipitant are as defined in any one of clauses 1 to 65. 67. The process of clause 65 or clause 66, wherein the process comprises: mixing the polymer with the organic additive, and treating the solution comprising the target metal species and the solvent with the mixture; or wherein the process comprises the following steps in order: (i) treating the solution with the organic additive; and (ii) treating the solution with the functionalised polymer. 68. The process of any of clauses 65 to 67, wherein treating the solution with the precipitant causes the complex to precipitate from the solution. 69. The process of any of clauses 65 to 68, wherein the process further comprises separating the complex from the solution. 70. The process of clause 69, wherein separating the complex from the solution comprises filtration, sedimentation, flotation, ora combination thereof. 71. The process of any of clauses 65 to 70, wherein the process further comprises removing the target metal species from a composition comprising the complex. 72. The process of clause 71, wherein removing the target metal species from the composition comprises forming a salt of the target metal species, optionally wherein forming the salt of the target metal species comprises adjusting the pH. 73. The process of clause 72, wherein the process further comprises separating the salt of the target metal species from the polymer, organic additive, and precipitant; optionally wherein separating the salt of the target metal species from the polymer, organic additive, and precipitant comprises filtering a composition comprising (i) a solution of the salt of the target metal species, and (ii) a precipitate comprising the polymer, organic additive, and / or precipitant, or (i) a solution of the polymer, organic additive and / or precipitant, and (ii) a precipitate comprising the salt of the target metal species. 74. The process of any of clauses 65 to 73, wherein the process further comprises recovering the polymer, organic additive, and / or precipitant; optionally wherein recovering the polymer, organic additive, and / or precipitant comprises adjusting the pH of a composition comprising the polymer, organic additive, and / or precipitant. 75. The process of any of clauses 65 to 74, wherein the solution comprises a plurality of metal species and the plurality of metal species comprises the target metal species and at least one non-target metal species, and wherein the process is for removing at least the target metal species from the plurality of metal species in the solution. 76. The process of any of clauses 65 to 75, wherein the solvent is aqueous. 77. The process of any of clauses 65 to 76, wherein the complex is a solution phase species. 78. The process of clause 77, wherein the complex is a monophasic solution. 79. Use of a functionalised polymer, an organic additive, and a precipitant, to remove a target metal species from a solution, wherein the solution comprises the target metal species, a solvent, and optionally non-target metal species that are different from the target metal species; wherein the organic additive is a hydrocarbyl group substituted by at least one heteroatom-containing group, and wherein the organic additive comprises at least one group that binds a metal species; wherein the functionalised polymer is a polymer with at least one covalently bound functional group, and at least one moiety that binds the target metal species; wherein the precipitant comprises at least one hydrophilic moiety and at least one hydrophobic moiety, and at least one group that binds the functionalised polymer and / or the target metal species. 80. The use of clause 79, wherein the target metal species, functionalised polymer, organic additive and / or precipitant are as defined in any one of clauses 1 to 64. 81. Use of an organic additive to modify the binding affinity of a metal species in solution for a functionalised polymer, wherein the solution comprises the metal species and a solvent, and wherein the organic additive is a hydrocarbyl group substituted by at least one heteroatom-containing group, wherein the organic additive comprises at least one group that binds a metal species, and wherein the functionalised polymer is a polymer with at least one covalently bound functional group, and at least one moiety that binds the metal species; wherein the binding affinity of the metal species for the functionalised polymer is modified relative to without the organic additive; and wherein the functionalised polymer and the organic additive are solution phase species. 82. The use of clause 81, wherein the functionalised polymer, organic additive, and / or metal species are as defined in any of clauses 1 to 64. 83. The use of clause 81 or 82, wherein the functionalised polymer and the organic additive are monophasic. 84. The use of any of clauses 81 to 83, wherein the organic additive increases the binding affinity of the metal species in solution for the functionalised polymer.

Claims

1. A product in the form of a solid aggregate comprising: a. a functionalised polymer which is a polymer with at least one covalently bound functional group, wherein the at least one covalently bound functional group is selected from:i. an aliphatic or aromatic hydrocarbon; ii. a N-heterocycle represented by formula (I) or (II):X3 X5 Ri ______ XiX3=X4X2.X. / X!wherein Xi, X2, X3, X4, and X5 in formula (I) and Xi, X2, X3, X4, and X5 in formula (II) are independently C or N, provided that at least one is N;wherein Ri and R2 are independently selected from -H, =O, -SRa, -ORa, =S, =N, -N(Ra)2, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -N(Rb)2, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, ora combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1.6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6alkenyl or OH; wherein Y is O or S; wherein x is an integer from 1 to 4; wherein n is 0 or an integer from 1 to 8; and wherein m is 0 or an integer from 1 to 8; oriii. a group represented by formula (III):r427 10 25R3 (III)wherein R3 and R4 are independently selected from -H, =O, -SRa, -ORa, =S, =N, -N(Ra)2, -N(Rb)3+A_, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -N(Rb)2, -N(Rb)3+A-, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SC(O) NRbRb, -OC(S)NRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, or a combination thereof;wherein X6 is -ORb, -SRb, -N(Rb)2, -N(Rb)3+A-, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SC(O) NRbRb, -OC(S)NRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, ora combination thereof;wherein Ra and Rb are independently selected from H, C1-6 alkyl or C-i. 6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6 alkenyl or OH; wherein Y is O or S; wherein A is an anion; wherein x is an integer from 1 to 4; wherein n is 0 or an integer from 1 to 8; and wherein m is 0 or an integer from 1 to 8, the polymer backbone being a polyelectrolytic polymer when in aqueous solution;b. an organic additive which is a hydrocarbyl substituted by at least two heteroatom-containing groups which differ from each other by the heteroatom and / or coordination environment, the at least two heteroatom-containing groups of the organic additive being:i. N-containing groups selected from amino groups, imino groups, amide groups, imide groups, diazonium compounds, amidine groups, hydrazide groups, carbazide groups, cyano groups, oxime groups, thioamide groups, N-heterocycles;ii. a N-containing group and a S-containing group, wherein the N-containing group is selected amino groups, imino groups, amide groups, imide groups, diazonium compounds, amidine27 10 25groups, hydrazide groups, carbazide groups, cyano groups, oxime groups, thioamide groups, and N-heterocycles; and wherein the S-containing group is selected from sulfonic acid groups, sulfinic acid groups, thioketone groups, thial groups, thioester groups, thioamide groups, and sulfhydryl groups; or Hi. a S-containing group and an O-containing group, wherein the S-containing group is selected from sulfonic acid groups, sulfinic acid groups, thioketone groups, thial groups, thioester groups, thioamide groups, and sulfhydryl groups; and wherein the O-containing group is selected from hydroxyl groups, carboxyl groups, and carbonyl groups;wherein the organic additive comprises at least one group that binds a metal species;c. a metal species that is a d-block metal species; andd. a precipitant, wherein the precipitant is a surfactant or a polymer which is anionic or cationic when in aqueous solution, the precipitant comprising at least one hydrophilic moiety and at least one hydrophobic moiety, and at least one group that binds the functionalised polymer and / or the metal species;wherein the functionalised polymer comprises at least one moiety that binds the metal species, wherein the functionalised polymer is bound to the organic additive, and the organic additive is bound to the metal species, and / or the functionalised polymer is bound to the metal species, and the organic additive is bound to the functionalised polymer and / or the metal species.

2. The product of claim 1, wherein one or more of the covalently bound functional groups of the polymer is a moiety that binds the metal species.

3. The product of any preceding claim, wherein the polymer backbone of the functionalised polymer is an organic polymer with N-containing groups.

4. The product of claim 3, wherein the polymer backbone comprises polyethyleneimine, polyvinylamine, polyallylamine, chitosan, polylysine, polyarginine, polyamide, polyacrylamide, ora combination thereof.

5. The product of any preceding claim, wherein the organic additive has a number average molecular weight of 1000 Da or less, as measured by gel permeation chromatography with a polystyrene standard.27 10 256. The product of any preceding claim, wherein the at least one covalently bound functional group is an alkyl or alkenyl group having 3 to 12 carbon atoms.

7. The product of any of claims 1 to 5, wherein the at least one covalently bound functional group of the polymer is a N-heterocycle represented by formula (I), wherein one of Xi, X2, X3, X4, and X5 is N, n is 0 and m is an integer from 1 to 4 or n is an integer from 1 to 4 and m is 0, wherein Ri and R2 are each independently selected from -H, =O, or =S.

8. The product of claim 7, wherein Ri and R2 are each -H.

9. The product of any of claims 1 to 5, wherein the at least one covalently bound functional group of the polymer is represented by formula (III), wherein Xe is -N(Rb)3+A_, Rb is C1-6 alkyl or C1-6alkenyl; A is an anion; n is an integer from 1 to 4 and m is an integer from 1 to 4; R3 is -H; and R4 is independently selected from -SH, -OH, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -OH, -SH, or a combination thereof.

10. The product of any preceding claim, wherein the organic additive is a thioamide, a C1-C12 hydrocarbyl substituted by at least two heteroatomcontaining groups selected from amine groups, imino groups, amide groups, sulfhydryls, carboxyl or carbonyl groups, a N-heterocycle substituted with one or more amino, imino, amide, imide, amidine, hydroazide, carbazide, cyano, oxime, or thioamide groups, ora combination thereof.

11. The product of any preceding claim, wherein the metal species comprises a metallic ion.

12. The product of claim 11, wherein the metallic ion is a metallic cation.

13. The product of any preceding claim, wherein the polymer backbone of thefunctionalised polymer is cationic when in aqueous solution and the precipitant is selected from an anionic surfactant, a polymer which is anionic in aqueous solution, and mixtures thereof.

14. The product of any preceding claim, wherein:a. the metal species is a d-block metal species;b. the polymer backbone of the functionalised polymer is a polyamine, a polyamide, or a combination thereof;c. the at least one covalently bound functional group is an aliphatic hydrocarbon, a group represented by formula (I) wherein one of Xi, X2, X3, X4, and X5 is N, n is 0 and m is an integer from 1 to 4 or n is an integer from 1 to 4 and m is 0, wherein Ri and R2 are each independently selected from -H, =O, or =S, or a group represented by27 10 25formula (III) wherein Xe is -N(Rb)3+A_, Rb is C1-6 alkyl or C1-6alkenyl; A is a halide anion; n is an integer from 1 to 4 and m is an integer from 1 to 4; R3 is -H; and R4 is independently selected from -SH, -OH, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -OH, -SH, ora combination thereof;d. the organic additive is a thioamide, a C1-C12 hydrocarbyl substituted by at least two heteroatom-containing groups selected from amine groups, imino groups, amide groups, sulfhydryls, carboxyl or carbonyl groups, a N-heterocycle substituted with one or more amino, imino, cyano or thioamide groups, ora combination thereof; ande. the precipitant is selected from an anionic surfactant, a polymer which is anionic in aqueous solution, and mixtures thereof.

15. A process for removing a target metal species from an aqueous solution, wherein the solution comprises the target metal species, a solvent comprising water, and non-target metal species, wherein the target metal species is a d-block metal species and wherein the non-target metal species is different from the target metal species, which process comprises treating the solution with a functionalised polymer and an organic additive to form a complex, the complex comprising the functionalised polymer and the target metal species, and treating the solution with a precipitant;wherein the organic additive is a hydrocarbyl group substituted by at least two heteroatom-containing groups which differ from each other by the heteroatom and / or coordination environment, the at least two heteroatom-containing groups of the organic additive being:a. N-containing groups selected from amino groups, imino groups, amide groups, imide groups, diazonium compounds, amidine groups, hydrazide groups, carbazide groups, cyano groups, oxime groups, thioamide groups, N-heterocycles;b. a N-containing group and a S-containing group, wherein the N-containing group is selected amino groups, imino groups, amide groups, imide groups, diazonium compounds, amidine groups, hydrazide groups, carbazide groups, cyano groups, oxime groups, thioamide groups, and N-heterocycles; and wherein the S-containing group is selected from sulfonic acid groups, sulfinic acid groups, thioketone groups, thial groups, thioester groups, thioamide groups, and sulfhydryl groups; orc. a S-containing group and an O-containing group, wherein the S-containing group is selected from sulfonic acid groups, sulfinic acid groups, thioketone groups, thial groups, thioester groups, thioamide groups, and sulfhydryl groups; and wherein the O-containing group is selected from hydroxyl groups, carboxyl groups, and carbonyl groups; wherein the organic additive comprises at least one group that binds a metal species;a. wherein the functionalised polymer is a polymer with at least one covalently bound functional group, the polymer backbone being a polyelectrolytic polymer when in aqueous solution, and at least one moiety that binds the target metal species; wherein the at least one covalently bound functional group is selected from:i. an aliphatic or aromatic hydrocarbon;ii. a N-heterocycle represented by formula (I) or (II):27 10 25iiR2wherein Xi, X2, X3, X4, and X5 in formula (I) and Xi, X2, X3, X4, and X5 in formula (II) are independently C or N, provided that at least one is N;wherein Ri and R2 are independently selected from -H, =O, -SRa, -ORa, =S, =N, -N(Ra)2, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -N(Rb)2, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, oracombination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1-6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6alkenyl or OH; wherein Y is O or S; wherein x is an integer from 1 to 4; wherein n is 0 or an integer from 1 to 8; and wherein m is 0 or an integer from 1 to 8; orHi. a group represented by formula (III):27 10 25wherein R3 and R4 are independently selected from -H, =O, -SRa, -ORa, =S, =N, -N(Ra)2, -N(Rb)3+A_, or a C1.6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -N(Rb)2, -N(Rb)3+A-, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SC(O) NRbRb, -OC(S)NRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, or a combination thereof;wherein X6 is -ORb, -SRb, -N(Rb)2, -N(Rb)3+A-, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SC(O) NRbRb, -OC(S)NRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, ora combination thereof;wherein Ra and Rb are independently selected from H, C1-6 alkyl or C-i. 6 alkenyl; wherein Rc is independently selected from H, C1.6 alkyl, C1-6 alkenyl or OH; wherein Y is O or S; wherein A is an anion; wherein x is an integer from 1 to 4; wherein n is 0 or an integer from 1 to 8; and wherein m is 0 or an integer from 1 to 8,wherein the precipitant is a surfactant or a polymer which is anionic or cationic when in aqueous solution, the precipitant comprising at least one hydrophilic moiety and at least one hydrophobic moiety, and at least one group that binds the functionalised polymer and / or the target metal species.

16. The process of claim 15, wherein treating the solution with the precipitant causes the complex to precipitate from the solution.27 10 2517. The process of claim 15 or claim 16, wherein the complex is a solution phase species.

18. The process of any of claims 15 to 17, wherein the complex is a monophasic solution.

19. The process of any of claims 15 to 18, wherein the organic additive is a thioamide, a C1-C12 hydrocarbyl substituted by at least two heteroatomcontaining groups selected from amine groups, imino groups, amide groups, sulfhydryls, carboxyl or carbonyl groups, a N-heterocycle substituted with one or more amino, imino, amide, imide, amidine, hydroazide, carbazide, cyano, oxime, or thioamide groups, ora combination thereof.

20. Use of a functionalised polymer, an organic additive, and a precipitant, to remove a target metal species from a solution, wherein the target metal species is a d-block metal species, wherein the solution comprises the target metal species, a solvent, and non-target metal species that are different from the target metal species; wherein the organic additive is a hydrocarbyl group substituted by at least two heteroatom-containing groups which differ from each other by the heteroatom and / or coordination environment, the at least two heteroatom-containing groups of the organic additive being:a. N-containing groups selected from amino groups, imino groups, amide groups, imide groups, diazonium compounds, amidine groups, hydrazide groups, carbazide groups, cyano groups, oxime groups, thioamide groups, N-heterocycles;b. a N-containing group and a S-containing group, wherein the N-containing group is selected amino groups, imino groups, amide groups, imide groups, diazonium compounds, amidine groups, hydrazide groups, carbazide groups, cyano groups, oxime groups, thioamide groups, and N-heterocycles; and wherein the S-containing group is selected from sulfonic acid groups, sulfinic acid groups, thioketone groups, thial groups, thioester groups, thioamide groups, and sulfhydryl groups; orc. a S-containing group and an O-containing group, wherein the S-containing group is selected from sulfonic acid groups, sulfinic acid groups, thioketone groups, thial groups, thioester groups, thioamide groups, and sulfhydryl groups; and wherein the O-containing group is selected from hydroxyl groups, carboxyl groups, and carbonyl groups; wherein the organic additive comprises at least one group that binds a metal species;a. wherein the functionalised polymer is a polymer with at least one covalently bound functional group, the polymer backbone being a polyelectrolytic polymer when in aqueous solution, and at least one moiety that binds the target metal species; wherein the at least one covalently bound functional group is selected from:i. an aliphatic or aromatic hydrocarbon;ii. a N-heterocycle represented by formula (I) or (II):iir227 10 25II r2wherein Xi, X2, X3, X4, and X5 in formula (I) and Xi, X2, X3, X4, and X5 in formula (II) are independently C or N, provided that at least one is N;wherein Ri and R2 are independently selected from -H, =O, -SRa, -ORa, =S, =N, -N(Ra)2, or a C1-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -N(Rb)2, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, ora combination thereof; wherein Ra and Rb are independently selected from H, C1-6 alkyl or C1.6 alkenyl; wherein Rc is independently selected from H, C1-6 alkyl, C1-6alkenyl or OH; wherein Y is O or S; wherein x is an integer from 1 to 4; wherein n is 0 or an integer from 1 to 8; and wherein m is 0 or an integer from 1 to 8; orHi. a group represented by formula (III):R427 10 2521.22.R3 (III)wherein R3 and R4 are independently selected from -H, =O, -SRa, -ORa, =S, =N, -N(Ra)2, -N(Rb)3+A_, or a 0-6 alkyl or alkenyl optionally substituted by one or more groups selected from -ORb, -SRb, -N(Rb)2, -N(Rb)3+A-, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SC(O) NRbRb, -OC(S)NRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, or a combination thereof;wherein X6 is -ORb, -SRb, -N(Rb)2, -N(Rb)3+A-, -C(O)Rb, -C(O)YRb, -C(O)NRbRb, -C(O)NRaNRbRb, -C(S)Rb, -C(S)YRb, -C(S)NRbRb, -C(S)NRaNRbRb, -C(NRc)Rb, -C(NRb)YRb, -C(NRb)NRbRb, -S(O)ORb, -S(O)2ORb, -S(O)2NRaNRbRb, -SC(O) NRbRb, -OC(S)NRbRb, -SXC(O) NRbRb, -OxC(S)NRbRb, -(NRb)xC(O)NRbRb, -(NRb)xC(S)NRbRb, ora combination thereof;wherein Ra and Rb are independently selected from H, C1-6 alkyl or C-i. 6 alkenyl; wherein Rc is independently selected from H, C1.6 alkyl, C1-6 alkenyl or OH; wherein Y is O or S; wherein A is an anion; wherein x is an integer from 1 to 4; wherein n is 0 or an integer from 1 to 8; and wherein m is 0 or an integer from 1 to 8, wherein the precipitant is a surfactant or a polymer which is anionic or cationic when in aqueous solution, the precipitant comprising at least one hydrophilic moiety and at least one hydrophobic moiety, and at least one group that binds the functionalised polymer and / or the target metal species. The use of claim 20, wherein the functionalised polymer and organic additive are monophasic.The use of claim 20 or claim 21, wherein the organic additive is a thioamide, a C1-C12 hydrocarbyl substituted by at least two heteroatom-containing groups selected from amine groups, imino groups, amide groups, sulfhydryls, carboxyl or carbonyl groups, a N-heterocycle substituted with one or more amino, imino, amide, imide, amidine, hydroazide, carbazide, cyano, oxime, or thioamide groups, ora combination thereof.

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