Organic-inorganic hybrid material for the selective extraction of gold and platinum group metals, and associated extraction and recovery methods

Abstract

The present invention relates to an organic-inorganic hybrid material comprising metal oxide particles bound (a) to at least one first compound corresponding to the general formula (I): [H2O3P-Zp-(CH2)m-Z'q-(Y)n-(CH2)m-Zp-PO3H2] wherein - m represents an integer such that 0 ≤ m ≤ 50, - n represents an integer such that 0 ≤ n ≤ 100, - p represents an integer equal to 0 or 1, - q represents an integer equal to 0 or 1, at least one of m, n, p and q being other than 0, - Y is selected from the group consisting of CH2CH2O, CH2CH2 and CF2CF2, - Z is selected from the group consisting of O, NH and CH2, and - Z' is O; and (b) to at least one second compound comprising an acid group and being an extractant of at least one metal M.

Description

[0001] Description

[0002] Title: Organic-inorganic hybrid material for the selective extraction of gold and platinum group metals, associated extraction and recovery processes

[0003] TECHNICAL FIELD OF THE INVENTION

[0004] The present invention relates to the field of extraction of one or more metals, denoted M, chosen from gold and platinum group metals, this or these metals M being contained in an aqueous phase.

[0005] It relates more particularly to a particular organic-inorganic hybrid material which can be used as an extractant to extract this or these metals M from the aqueous phase in which this or these metals M are present.

[0006] The invention also relates to a method for extracting this or these metals M contained in the aqueous phase, this extraction method comprising bringing this aqueous phase into contact with a phase comprising this particular organic-inorganic hybrid material.

[0007] The invention also relates to a method for recovering this or these metals M which implements the extraction process just mentioned.

[0008] The aqueous phase from which this or these metals M can be extracted, or from which they can be recovered, may in particular be a solution resulting from hydrometallurgical treatments of mineral deposits or urban mines.

[0009] The present invention finds particular application in the treatment of natural ores and / or industrial waste, such as waste electrical and electronic equipment, with a view to recovering gold and platinum group metals present in the latter.

[0010] STATE OF THE ART

[0011] The platinum group metals, also known as platinum group metals, refer to the periodic table elements that are platinum (Pt), palladium (Pd), osmium (Os), iridium (Ir), ruthenium (Ru) and rhodium (Rh).

[0012] Platinum group metals (PGMs) are widely used in many chemical industry processes, for example as catalysts, but also in renewable energy technologies, particularly in fuel cells, and in energy storage technologies, notably in redox flow batteries. PGMs are also used in jewelry, just like gold (Au). There are three main sources of supply for PGMs and gold: extraction from primary resources (old mines or new deposits), extraction from secondary resources (mining waste, red mud, etc.), and extraction from urban mines.

[0013] The exploration and exploitation of mineral deposits still relies on traditional extraction processes which have a significant impact on the environment and human health due to the implementation of often polluting processes, the production of waste and the use of harmful chemical reagents.

[0014] The concept of urban mining aims to transform already collected waste into resources, by recovering gold and platinum group metals contained in industrial and domestic waste, such as waste electrical and electronic equipment, also known as "WEEE" or "D3E".

[0015] If it is free from the issues of radiation protection, treatment of mining waste and environmental protection with the associated binding directives, the urban mine is, moreover, a world-class deposit, without mining rights and benefiting from proven supply facilities.

[0016] In an urban mine, used waste is collected and subjected to advanced recycling processes. These processes typically involve several steps, including dismantling equipment, separating components and metals, and then purifying them to obtain metallic species in the form of metal salts, metal oxides, or metals. The recovered metallic species can then be used in the manufacture of new products, thus reducing dependence on traditional mining.

[0017] Recycling from urban mines offers several advantages. It reduces the volume of electronic waste in landfills, thus contributing to resource conservation and pollution reduction. Furthermore, it allows for the recovery of precious and rare metals that would otherwise be lost, thereby reducing pressure on traditional mining deposits. However, this recycling is not entirely without drawbacks. Firstly, the efficient collection of this electronic waste on a large scale remains a challenge in many countries, and secondly, the complex and costly recycling processes required to recover the metals can still present technical and economic challenges.

[0018] Among these challenges, the issue of valorizing the solutions obtained from the hydrometallurgical treatment of WEEE, which contain metals at concentrations below a few hundred ppm, remains an unresolved problem. The inability to extract precious metals, such as gold and platinum group metals, contained in very low concentrations in these solutions, results in considerable financial losses for players in the recycling industry.

[0019] For obvious reasons, the recovery of gold and platinum group metals from urban mines has undeniable appeal, both economically, given the high cost of these metals, and environmentally.

[0020] Thus, the recycling of WEEE waste constitutes an unconventional and alternative source of access to gold and platinum group metals, which is part of an economic and sustainable development approach.

[0021] There are several physical and / or chemical processes for the extraction of these metals, including processes using ion exchange resins, membrane ultrafiltration, flocculation and solvent extraction (liquid / liquid extraction) or adsorption (solid / liquid extraction).

[0022] Among these processes, adsorption extraction, in which compounds in solution in a liquid phase are separated from other elements present in that liquid phase by selective adsorption onto a solid phase based on their physicochemical properties, is considered the most efficient process due to its low cost, flexibility, and simplicity of design and implementation. It is primarily for these reasons that this extraction process is the most commonly used in industry. Furthermore, adsorption extraction does not produce harmful byproducts or concentrated toxic sludge and does not require high energy costs. However, for economic, environmental, and sustainable development reasons, selectivity and recyclability are essential parameters.

[0023] It is therefore necessary to propose adsorbents that allow for the efficient and selective extraction of compounds of interest, such as gold and platinum group metals, which are present in the solutions obtained after hydrometallurgical treatment of WEEE.

[0024] The publication by S. Asaad et al. ("New Carbamoyl Surface-Modified ZrO2 Nanohybrids for Selective Au Extraction from E-Waste", Molecules, 2023, 28, 2219), referenced [1] in the remainder of this description, proposes an organic-inorganic hybrid material comprising zirconia ZrC particles surface-modified by organic ligands, specifically phosphonic acid compounds containing a monocarbamoyl or dicarbamoyl group, for the adsorption extraction of Au(III) gold and Pd(III) palladium from acidic aqueous solutions. Publication [1] more specifically reports the extraction of Au(III) using a solid phase consisting of ZrO2 nanoparticles bonded to di- / V, / V-butyl carbamoyl pentylphosphonic acid (DBCPPA) as an organic-inorganic hybrid material.This extraction proved not only effective but also remarkably selective, capturing only gold Au(lll) while this metal was present only in minute concentrations (on the order of 10 ppm) in the initial aqueous phase which also contained Pd, Cu, Ni and Fe.

[0025] However, this organic-inorganic hybrid material described in publication [1] has a limitation in terms of recyclability. Indeed, to reuse this material, it is necessary to perform a washing phase in a basic medium after gold extraction and subsequent de-extraction. This washing step, however, leads to a significant reduction in the material's extraction performance during a second extraction and de-extraction cycle.

[0026] It is on the basis of this observation that the Inventors have therefore set themselves the goal of providing a new family of extractants which, in addition to enabling efficient and selective extraction and recovery of these metals, in particular gold and platinum group metals, are recyclable.

[0027] Another objective of the invention is to provide a process for the efficient and selective extraction and recovery of gold and platinum group metals from an aqueous phase that may originate from solutions resulting from hydrometallurgical processing of mineral deposits or urban mines, particularly WEEE (Waste Electrical and Electronic Equipment). Such extractions and recoveries should be feasible regardless of the initial concentrations of gold and platinum group metals in these solutions.

[0028] Another aim of the invention is to propose a particular organic-inorganic hybrid material enabling the preparation of this new family of extractants.

[0029] DESCRIPTION OF THE INVENTION

[0030] The goals stated above, as well as others, are achieved, in the first place, by a particular organic-inorganic hybrid material which, to the knowledge of the Inventors, has not been described to date.

[0031] According to the invention, this particular organic-inorganic hybrid material comprises metal oxide particles bonded to at least one first compound corresponding to the following general formula (I):

[0032] [H2O3P-Zp-(CH2) m -Z' q -(Y) n -(CH2) m -Zp-PO3H2] (I) in which - m represents an integer such that 0 < m < 50,

[0033] - n represents an integer such that 0 < n < 100,

[0034] - p represents an integer equal to 0 or 1,

[0035] - q represents an integer equal to 0 or 1, at least one of m, n, p and q being different from 0, advantageously at least two of m, n, p and q being different from 0,

[0036] - Y is chosen from the group consisting of CH2CH2, CH2CH2O and CF2CF2, advantageously when p = q = 0, Y is CH2CH2O or CF2CF2, Y being preferably CH2CH2O,

[0037] - Z is chosen from the group consisting of O, NH and CH2, advantageously Z is chosen from the group consisting of O and NH, and

[0038] - Z' is O.

[0039] This organic-inorganic hybrid material according to the invention, which comprises metal oxide particles linked to at least one first compound corresponding to the general formula (I), is of major interest in that it will be able to react with at least one second compound to form a family of extractants, as will be seen later.

[0040] In a first embodiment, the organic-inorganic hybrid material according to the invention comprises metal oxide particles that are linked to at least a first compound that corresponds to the general formula (I) in which n = p = q = 0.

[0041] In this first embodiment, the first compound(s) then correspond to the following particular formula(s):

[0042] [H2O3P-(CH2)2 m -PO3H2] (the)

[0043] In an advantageous variant of this first embodiment, m is such that 2 < m < 35. In a preferred variant, m is such that 3 < m < 25.

[0044] In a second embodiment, the organic-inorganic hybrid material according to the invention comprises metal oxide particles that are linked to at least a first compound that corresponds to the general formula (I) in which n * 0 and p = q = 0.

[0045] In this second embodiment, the first compound(s) then correspond to the following particular formula (lb):

[0046] [H2O3P-(CH2) m -(Y) n -(CH2) m -PO3H2] (lb)

[0047] In an advantageous variant of this second embodiment, m is such that 1 < m < 4. In a preferred variant, m is such that 2 < m < 3 and, more preferably, m = 2. In an advantageous variant of this second embodiment, n is such that 1 < n < 12. In a preferred variant, n is such that 2 < n < 10.

[0048] As previously stated, Y is chosen from the group consisting of CH2CH2, CH2CH2O and CF2CF2. Preferably, Y is CF2CF2.

[0049] In a third embodiment, the organic-inorganic hybrid material according to the invention comprises metal oxide particles that are linked to at least a first compound that corresponds to the general formula (I) in which n = q = 0 and p = l.

[0050] In this third embodiment, the first compound(s) then correspond to the following particular formula (lc):

[0051] [H2O3P-Z-(CH2)2 m -Z-PO3H2] (lc)

[0052] In an advantageous variant of this third embodiment, m is such that 1 < m < 20. In a preferred variant, m is such that < m < 5 and, more preferably, such that 2 < m < 4.

[0053] As previously stated, Z is chosen from the group consisting of O, NH and CH2. Z is advantageously O or NH and, more preferably, NH.

[0054] In a fourth embodiment, the organic-inorganic hybrid material according to the invention comprises metal oxide particles that are linked to at least a first compound that corresponds to the general formula (I) in which n * 0 and q = p = 1.

[0055] In this fourth embodiment, Z' being O, the first compound(s) then correspond to the following particular formula (ld):

[0056] [H2O3P-Z-(CH2) m -O-(Y)n-(CH2) m -Z-PO3H2] (ld)

[0057] In an advantageous variant of this fourth embodiment, m is such that

[0058] 1 < m < 4. In a preferred variant, m is such that 2 < m < 3 and, more preferably, m = 2.

[0059] In an advantageous variant of this fourth embodiment, n is such that 1 < n < 40. In a preferred variant, n is such that 2 < n < 20.

[0060] As previously stated, Z is chosen from the group consisting of O, NH and CH2 and Y is chosen from the group consisting of CH2CH2, CH2CH2O and CF2CF2.

[0061] Z is advantageously O or NH and, more preferably, NH.

[0062] Preferably, Y is CH2CH2O.

[0063] In a fifth embodiment, the organic-inorganic hybrid material according to the invention comprises metal oxide particles that are bonded to at least one first compound that corresponds to the general formula (I) in which n * 0, p = 0 and q = 1. In this fifth embodiment, q = 1 and Z' being O, the first compound(s) then correspond to the following particular formula (the): [H2O3P-(CH2) m -O-(Y)n-(CH2) m -PO3H2] (the)

[0064] In an advantageous variant of this fifth embodiment, m is such that 1 < m < 4. In a preferred variant, m is such that 2 < m < 3 and, more preferably, m = 3.

[0065] As previously stated, Y is chosen from the group consisting of CH2CH2, CH2CH2O and CF2CF2. Preferably, Y is CH2CH2O.

[0066] In a particularly advantageous variant of this fifth embodiment, the first compound is poly(ethylene glycol) α,co-bisphosphonic acid, which corresponds to the particular formula (the 1 ) following, in which m = 3 and Y is CH2CH2O.

[0067] [H2O3P-(CH2)3-O-(CH2CH2O)n-(CH2)3-PO3H2] (l-e')

[0068] In these formulas (the) and (the 1 ), n can be such that 20 < n < 80 and, in particular, such that 30 < n < 70.

[0069] In a sixth embodiment, the organic-inorganic hybrid material according to the invention comprises metal oxide particles that are bonded to at least one first compound corresponding to the general formula (I) in which n > 2, with m, p, and q as defined above. The first compound(s) then correspond to the general formula (I) in which:

[0070] - m represents an integer such that 0 < m < 50,

[0071] - n represents an integer such that 2 < n < 100,

[0072] - p represents an integer equal to 0 or 1,

[0073] - q represents an integer equal to 0 or 1,

[0074] - Y is chosen from the group consisting of CH2CH2O, CH2CH2 and CF2CF2, Y preferably being CH2CH2O,

[0075] - Z is chosen from the group consisting of O, NH and CH2, and

[0076] - Z' is O.

[0077] As in the formulas (the) and (the 1) of the fifth embodiment, in this sixth embodiment, n can be such that 20 < n < 80 and, in particular, such that 30 < n < 70.

[0078] In the case where, in this sixth embodiment but also in formulas (I), (lb), (ld), (le) and (le 1 The first compound(s) comprise at least two Y groups, these Y groups being selected from the group consisting of CH2CH2O, CH2CH2, and CF2CF2. These Y groups may be identical or different. In an advantageous embodiment, the Y groups are identical and, preferably, are CH2CH2O. The organic-inorganic hybrid material according to the invention comprises metal oxide particles that are bonded to at least one first compound corresponding to the general formula (I) described above.

[0079] The metallic oxide of the particles may in particular be an oxide of a metal from the p-block or the d-block.

[0080] When the metal is a p-block metal (the p-block corresponding to the elements in groups 13 to 18 of the periodic table), also called a poor metal or post-transition metal, the metal oxide can notably be chosen from Al2O3 and SnC.

[0081] When the metal is a d-block metal (the d-block corresponding to the elements in groups 3 to 12 of the periodic table), also called a transition metal, the metal oxide can notably be chosen from ZrC, HfC, TiC, ZnO, FezOa and NbîOs.

[0082] In an advantageous variant, the metal oxide is chosen from the group consisting of ZrC, HfC, TiC, ZnO, SnU2, Fe2U3, Al2O3 and Nb2O5. Preferably, the metal oxide is ZrU2.

[0083] In a particular embodiment, the metal oxide is in the form of particles having an average number size d5o of between 1 nm and 100 nm, advantageously between 3 nm and 50 nm and, preferably, between 5 nm and 15 nm.

[0084] In a particular embodiment, the molar ratio between the metal oxide and the first compound, denoted metal oxide:first compound, is between 30000:1 and 200:1, advantageously between 20000:1 and 300:1 and, preferably, between 10000:1 and 500:1.

[0085] The present invention relates, secondly, to a specific organic-inorganic hybrid material which corresponds to a new family of extractants.

[0086] According to the invention, this specific organic-inorganic hybrid material comprises the particular organic-inorganic hybrid material just defined and further comprises at least one second compound also bound to the metal oxide particles, this second compound being an extractant of at least one metal M.

[0087] In other words, this specific organic-inorganic hybrid material comprises metal oxide particles that are bonded:

[0088] (a) to at least a first compound which corresponds to the following general formula (I): [H2O3P-Zp-(CH2) m -Z' q -(Y) n -(CH2) m -Zp-PO3H2] (I) in which

[0089] - m represents an integer such that 0 < m < 50,

[0090] - n represents an integer such that 0 < n < 100, - p represents an integer equal to 0 or 1,

[0091] - q represents an integer equal to 0 or 1, at least one of which m, n, p and q is different from 0,

[0092] - Y is chosen from the group consisting of CH2CH2O, CH2CH2 and CF2CF2, Y preferably being CH2CH2O,

[0093] - Z is chosen from the group consisting of O, NH and CH2, and

[0094] - Z' is O, and, moreover,

[0095] (b) to at least a second compound, this second compound being an extractant of at least one metal M.

[0096] The Inventors have found that, surprisingly and unexpectedly, the use of this specific organic-inorganic hybrid material defined above, which includes at least one second compound that is an extractant of a metal M, makes it possible to extract, efficiently and selectively, this metal M present in an aqueous phase, even if this metal M is present there only in low concentrations, or even in trace amounts.

[0097] The specific organic-inorganic hybrid material according to the invention therefore comprises the particular organic-inorganic hybrid material described above, it being specified that the advantageous, preferential, and more preferential characteristics of this particular organic-inorganic hybrid material, such as those relating to compounds of formulas (I), (la), (lb), (lc), (ld), (le), and (le 1 ) and metallic oxides, can be taken alone or in combination.

[0098] The specific organic-inorganic hybrid material according to the invention also comprises at least one second compound which is linked to the metal oxide particles and which is an extractant of the metal(s) M.

[0099] To avoid any ambiguity, it is specified that, in the preceding and following text, "extractant" means any active compound and principal responsible for the transfer of one or more solutes from one phase to another phase, as defined in particular in the monograph of Techniques de l'ingénieur (Internet reference J2760-December 1998).

[0100] The second compound is a compound which includes, on the one hand, a functional group enabling it to bind, typically by covalent bond, to metal oxide particles and, on the other hand, complexing properties to extract the metal(s) M.

[0101] This second compound, also called the ligand, may include an acid group as its functional group. In an advantageous variant, this second compound is chosen from the group consisting of phosphoric acids, phosphonic acids, carboxylic acids, and sulfonic acids. In a preferred variant, this second compound is a phosphoric acid or a phosphonic acid.

[0102] The complexing properties of the second compound are adapted to the metal(s) M to be extracted.

[0103] Thus, the second compound may include a monocarbamoyl group or a dicarbamoyl group.

[0104] As examples, to extract gold from an aqueous phase, the second compound can be chosen from among the organic compounds, or ligands, described in publication [1], including / V, / V-diethylcarbamoyl methylphosphonic acid (DECMPA), / V, / V-dipropylcarbamoyl methylphosphonic acid (DPCMPA), / V, / V-dioctylcarbamoyl methylphosphonic acid (DOCMPA), / V, / V-bis(2-ethylhexyl)carbamoyl methylphosphonic acid (DEHCMPA), di- / V, / V-butylcarbamoyl butylphosphonic acid (DBCBPA) or di- / V, / V-butylcarbamoyl pentylphosphonic acid (DBCPPA).

[0105] In a particular embodiment, the molar ratio between the metal oxide and the second compound, denoted metal oxide:second compound, is between 500:1 and 10:1, advantageously between 200:1 and 20:1 and, preferably, between 100:1 and 50:1.

[0106] Thirdly, the present invention relates to a process for extracting one or more metals M selected from gold and platinum group metals contained in an aqueous phase Al, this process comprising at least one step of contacting the aqueous phase Al with a phase A2, thereby obtaining, after a phase separation step, an aqueous phase Al' and a phase A2' comprising the metal(s) M.

[0107] According to the invention, phase A2 comprises the specific organic-inorganic hybrid material defined above as an extractant.

[0108] In a particular embodiment, phase A2 consists of the specific organic-inorganic hybrid material defined above as the extractant.

[0109] The present invention relates, fourthly, to a process for recovering one or more metals M selected from gold and platinum group metals contained in an aqueous phase Al, this process comprising the following successive steps (a) and (b):

[0110] (a) the extraction of the metal(s) M from the acidic aqueous phase Al by an extraction process; and

[0111] (b) the de-extraction of the metal(s) M. In the extraction process according to the invention, step (a) of extraction is carried out by the extraction process as defined above.

[0112] In other words, the recovery process according to the invention comprises the following steps:

[0113] (a) a step of contacting the aqueous phase Al with a phase A2, thereby obtaining, after a phase separation step, an aqueous phase Al' and a phase A2' comprising the metal(s) M, phase A2 comprising the specific organic-inorganic hybrid material as an extractant; and

[0114] (b) the removal of the metal(s) M present in phase A2' as obtained at the end of step (a), thereby obtaining a phase A2" from which the metal(s) M have been removed.

[0115] The common characteristics of the extraction and recovery processes which are the subject of the present invention will be described below.

[0116] The choice of a phase A2 which includes the specific organic-inorganic hybrid material according to the invention as defined above makes it possible to extract and, where appropriate, recover, efficiently and selectively, gold and / or one or more platinum group metals, and in particular gold, from an acidic aqueous phase Al which contains it or them, regardless of the concentration of gold and platinum group metal(s), in particular when their concentration in the aqueous phase Al is low (on the order of a few ppm).

[0117] In particular, the extraction and recovery processes according to the invention are characterized by extraction and, consequently, recovery performances that are at least equal to, if not greater than, those that can be achieved with extraction and recovery processes using the organic-inorganic hybrid material such as that described in document [1],

[0118] The processes according to the invention also allow the extraction and recovery of gold and / or one or more platinum group metals present in an aqueous phase with remarkable selectivity towards other metals and impurities that are also present in this aqueous phase Al, in particular towards copper, iron or nickel.

[0119] In one embodiment of the extraction and recovery processes according to the invention, the aqueous phase Al is a solution resulting from the acid attack, typically by one or more inorganic acids, of a natural ore - typically from mining deposits - or from an urban mine comprising one or more metals M chosen from gold (Au) and the platinum group metals which are platinum (Pt), palladium (Pd), osmium (Os), iridium (Ir), ruthenium (Ru) and rhodium (Rh).

[0120] It is recalled that, as previously stated, "urban mine" refers to the source which comes in particular from the recycling of industrial and domestic waste such as waste electrical and electronic equipment, also known as "WEEE" or "D3E".

[0121] In an advantageous variant, the metal M is chosen from gold and palladium. In a preferential variant, this metal M is gold.

[0122] In one embodiment of the extraction and recovery processes according to the invention, the aqueous phase Al has a total molar concentration of metals M of at least 0.01 ppm, in particular between 0.01 ppm and 200 ppm, advantageously between 0.1 ppm and 100 ppm and, preferably, between 0.1 ppm and 50 ppm.

[0123] In a more particularly preferred embodiment, the process according to the invention further comprises, after step (b), at least one additional cycle comprising steps (b 1) and (b") following successive:

[0124] (b 1 ) the extraction of the metal(s) M comprising at least one step of contacting the aqueous phase Al with the phase A2" as obtained at the end of step (b), thereby obtaining, after a phase separation step, an aqueous phase Al" and a phase A2" comprising the metal(s) M; and

[0125] (b") the extraction of the metal(s) M present in phase A2'" as obtained at the end of step (b 1 ).

[0126] It is observed, unexpectedly and surprisingly, that the specific organic-inorganic hybrid material according to the invention can be reused for the implementation of one or more other extraction / de-extraction cycles, unlike the material described in publication [1],

[0127] It is, in fact, entirely possible to use phase A2, as obtained at the end of step (b) and from which the metal(s) M have been extracted, to carry out at least a second extraction followed by a second recovery of the metal(s) M present in an aqueous phase A1 containing them. In particular, it is not necessary to carry out a washing step on this phase A2.

[0128] Other advantages and features of the present invention will become apparent from the following examples, which relate to the synthesis of organic-inorganic hybrid materials according to the invention, as well as to tests demonstrating the ability of these materials to extract gold from aqueous phases. It should be noted that these examples are given solely to illustrate the objects of the invention and do not in any way constitute a limitation thereof.

[0129] BRIEF DESCRIPTION OF THE FIGURES

[0130] Figure 1 illustrates Fourier transform infrared (FTIR) spectra as a function of wavenumber (denoted θ and expressed in cm⁻¹). 1 ) of the ZrÛ2-PEG2P particles from example 1.

[0131] Figure 2 illustrates the thermogravimetric analysis (TGA) curves showing the mass variation (noted Am and expressed in % mass) as a function of temperature (noted T and expressed in °C) of the ZrOî particles from the starting suspension and the ZrÛ2-PEG2P particles from Example 1.

[0132] Figure 3 illustrates the FTIR spectra as a function of the wavenumber (denoted θ and expressed in cm⁻¹). 1 ) of ZrO2-PEG2P-L particles 7 (ZrO2:PEG2P molar ratios of 5000:1, 2500:1, 1000:1 and 750:1) from example 2.

[0133] Figure 4 illustrates the FTIR spectra as a function of the wavenumber (denoted θ and expressed in cm⁻¹). 1 ) ZrC particles from the starting suspension, ligand L7 , ZrU2-PEG2P particles and corresponding functionalized ZrC2-PEG2P-L particles 7 (ZrO2:PEG2P molar ratios of 1000:1 and ZrO2-PEG2P:L 7 of 50:1) examples 1 and 2.

[0134] Figure 5 illustrates the solid-state NMR spectra of the 31 P of PEG2P, of ZrC-PEG2P particles and of corresponding functionalized ZrC>2-PEG2P-L particles 7 (ZrO2:PEG2P molar ratios of 1000:1 and ZrO2-PEG2P:L 7 of 50:1) examples 1 and 2.

[0135] Figure 6 illustrates the TGA curves showing the mass variation (denoted Am and expressed as % mass) as a function of temperature (denoted T and expressed in °C) of the ZrC particles from the initial suspension, Zr²⁻PEG²⁺ particles, and the corresponding functionalized Zr²⁻PEG²⁺ particles. 7 (ZrC>2:PEG2P molar ratios of 1000:1 and ZrC>2-PEG2P:L 7 of 50:1) examples 1 and 2.

[0136] Figure 7 illustrates the X-ray diffraction (XRD) spectra showing the evolution of the intensity of the diffracted X-rays as detected (denoted I and expressed as the number of counts) as a function of the two-theta diffraction angle of the X-ray beam (denoted 20 and expressed in °) of the ZrC particles from the initial suspension and of functionalized ZrC>2-PEG2P-L particles 7 (ZrC>2:PEG2P molar ratios of 1000:1 and ZrC>2-PEG2P:L 7 of 50:1) of example 2.

[0137] Figures 8A and 8B correspond to cryo-transmission electron microscopy (Cryo-TEM) images of the ZrC particles from the initial suspension (Figure 8A) and of the functionalized ZrU2-PEG2P-L particles. 7 (ZrO2:PEG2P molar ratios of 1000:1 and ZrO2-PEG2P:L 7 of 50:1) from example 2 (figure 8B).

[0138] Figure 9 is a histogram illustrating the percentage extraction (denoted E and expressed as a percentage) of Au(lll) obtained with the implementation of ZrO2-PEG2P-L functionalized particles 7 (ZrO2:PEG2P molar ratios of 5000:1, 2500:1, 1000:1 and 750:1 and ZrO2-PEG2P:L 7 of 50:1) obtained in example 2.

[0139] Figure 10 is a histogram illustrating the percentage of extraction (denoted E and expressed as a percentage) and de-extraction (denoted Desex and expressed as a percentage) of Au(lll) using 4 successive extraction and de-extraction cycles with ZrC>2-PEG2P- L functionalized particles 7 (ZrC2:PEG2P molar ratios of 1000:1 and ZrC2-PEG2P:L 7 of 50:1) of example 2.

[0140] Figure 11 is a histogram illustrating the percentage of extraction (denoted E and expressed as a percentage) and de-extraction (denoted Desex and expressed as a percentage) of Au(lll) implementing two successive extraction and de-extraction cycles with ZrC-L functionalized particles 7 (ZrÛ2:L molar ratio 7 of 50:1).

[0141] DETAILED DESCRIPTION OF SPECIFIC METHODS OF IMPLEMENTATION

[0142] Synthesis of compounds according to the invention

[0143] The organic-inorganic hybrid nanoparticles according to the invention were prepared from the following compounds:

[0144] - α,co-bisphosphonic acid of poly(ethylene glycol), hereinafter referred to as PEG2P, marketed by Specific Polymers under the reference SP-1P-1-003 (CAS 1613144-46-9, 2000-2500 g / mol) corresponding to the formula (the 1 ) below with n ranging from 40 to 50 (40 < n < 50):

[0145] - zirconium dioxide ZrC marketed by the company Mathym SAS (Champagne-au-Mont-d'Or, France) in the form of an aqueous suspension of ZrC, the aqueous suspension having a pH between 4 and 5 and comprising 20% ​​mass of ZrC in the form of particles with a particle size less than or equal to 6 nm (CAS 215-227-2)

[0146] - di- / V, / V-butylcarbamoyl butylphosphonic acid (DBCBPA), hereinafter referred to as L 7 , provided by the Marcoule Institute of Separative Chemistry (ICSM). Example 1: Synthesis of ZrU2-PEG2P particles according to the invention

[0147] To 5 mL of the aqueous suspension of ZrO2 (20% mass, 6 nm) in a 25 mL flask, different quantities of PEG2P (1 mg, 4 mg, 7.3 mg, 20 mg, 25 mg and 36 mg) in solution in 2 mL of demineralized water were added dropwise under magnetic or mechanical stirring (700 rpm), with the aim of preparing 7 batches of ZrO2-PEG2P particles having different ZrO2:PEG2P molar ratios, which are respectively 20000:1, 5000:1, 2500:1, 1500:1, 1000:1, 750:1 and 500:1.

[0148] The mixtures (or slurries) were then placed under magnetic stirring for 24 h at room temperature (between 18 °C and 25 °C).

[0149] These mixtures were then dried under vacuum with continuous rotation in a rotary evaporator for 24 h. The white powders were then collected with mass yields of 90%. They were used without further purification for the second functionalization step with the extracting ligand (for the implementation of pathway a).

[0150] All the ZrO2-PEG2P powders thus synthesized were characterized by Fourier transform infrared spectroscopy (FTIR), BET, solid-state NMR. 31 P, and thermogravimetric analysis (TGA).

[0151] The FTIR spectra and TGA curves are shown in Figures 1 and 2, respectively.

[0152] The data from the BET and solid NMR analyses of 31 The P of the synthesized ZrC>2-PEG2P powder particles and, where applicable, of the ZrO2 particles from the starting suspension, are reported in Table 1 below:

[0153] Table 1

[0154] Example 2: Synthesis of ZrO2-PEG2P-L particles 7 according to the invention

[0155] The functionalization of the ZrO2-PEG2P particles from example 1 by the ligand L 7 the above was carried out via two routes, route a and route b.

[0156] Route a To an aqueous suspension of each of the 7 batches of ZrC-PEGZP particles (5 mmol), 0.1 mmol of DBCBPA (L 7 ) in 1 mL of ethanol in order to prepare 7 new batches of ZrÛ2-PEG2P-L particles 7 all exhibiting a ZrO2-PEG2P:L molar ratio 7 of 50:1.

[0157] The mixtures were then stirred magnetically or mechanically (700 rpm) for 24 h at room temperature (between 18 °C and 25 °C).

[0158] The solid phase of each batch was separated by centrifugation and washed three times with 10 mL of water. A centrifugation phase was applied after each washing step. Finally, the hybrid ZrÛ2-PEG2P-L nanomaterials 7 were dried at 70 °C for 24 h to obtain white powders with mass yields greater than 95%.

[0159] Lane b

[0160] The operating protocol of the aa route was repeated but starting directly from the mixtures (slurries) obtained in example 1, before separation of the solid and liquid phases.

[0161] ZrC>2-PEG2P-L powders 7 The synthesized compounds were characterized by Fourier transform infrared spectroscopy (FTIR), by measuring their specific surface area using the BET method, and by solid-state NMR. 31 P, by thermogravimetric analysis, by powder XRD analysis and by cryo-transmission electron microscopy (Cryo-TEM).

[0162] FTIR spectra of ZrC>2-PEG2P-L powders 7 such as those obtained by route a and in which the molar ratios ZrC>2:PEG2P are respectively 5000:1, 2500:1, 1000:1 and 750:1) are shown in Figure 3.

[0163] The data from the BET and solid NMR analyses of 31 P of these powders ZrC>2-PEG2P-L 7 in which the molar ratios ZrC>2:PEG2P are respectively 5000:1, 2500:1, 1000:1 and 750:1 synthesized via pathway a are reported in Table 2 below:

[0164] Table 2

[0165] The FTIR spectra of the ZrÛ2 powder from the starting suspension, of the ligand L 7 , ZrC>2-PEG2P particles (ZrC>2:PEG2P molar ratio of 1000:1) from Example 1 and the corresponding functionalized ZrC-PEGZP-L particles 7 from example 2 (way a) are shown in the figure

[0166] 4.

[0167] The data from the BET and solid NMR analyses of 31 P of ZrC-PEGZP and ZrC>2-PEG2P-L powders 7 (with a ZrU2:PEG2P molar ratio of 1000:1) synthesized via pathways a and b are shown in Table 3 below:

[0168] Table 3

[0169] Solid-state NMR spectra of 31 P, TGA curves and XRD spectra of functionalized particles ZrÛ2-PEG2P-L 7 (ZrC2:PEG2P molar ratios of 1000:1 and ZrC2-PEG2P:L 7 of 50:1) of example 2 (way a) are respectively shown in figures 5 to 7.

[0170] The Cryo-MET images in figures 8A and 8B highlight the formation of aggregates illustrating the development of the three-dimensional network between the ZrÛ2 nanoparticles and the α,co-bisphosphonic acid ligands of poly(ethylene glycol) or PEG2P.

[0171] Example 3: Extraction and recovery of Au(lll) from an aqueous phase Al by a phase A2 comprising ZrO2-PEG2P-L particles 7 according to the invention

[0172] Extraction of Au(lll)

[0173] ZrÛ2-PEG2P-L functionalized particles 7 of example 2 prepared according to route a and in which the ZrC>2:PEG2P molar ratios are 5000:1, 2500:1, 1000:1 and 750:1 of 1000:1, the molar ratio always being ZrC>2-PEG2P:L 7 of 50:1, were implemented according to the operating protocol described below.

[0174] Extractions are performed by contacting aqueous Al phases containing Au(l) with a solid A2 phase consisting of functionalized ZrC2-PEG2P-L particles 7 (path a).

[0175] The aqueous Al phases are formed from aqueous solutions comprising 10 ppm of Au(lll) and having a pH between 2 and 3.

[0176] To do this, 50 mg of ZrC>2-PEG2P-L particles 7 (solid phase A2) were introduced into reactors each containing 20 mL of aqueous phase Al. The suspensions were stirred at 300 rpm, at room temperature (between 18 °C and 25 °C) for 24 h.

[0177] The supernatant solutions (aqueous phases Al') were then separated from the solid phase A2' by centrifugation at 10000 rpm for 10 min.

[0178] The final concentrations of Au(lll) in the aqueous phase Al' were determined by measuring the distribution coefficients of the species in solution, by inductively coupled plasma optical emission spectrometry (ICP-OES).

[0179] The extraction percentages, denoted E (%), were determined by the following equation:

[0180] (Ci — Cf)

[0181] E (%) = x lOO

[0182] Ci, where Ci = concentration of the metallic element M (here, Au) in the aqueous phase Al before extraction (in ppm), and

[0183] Cf = concentration of the metallic element M (here, Au) in the aqueous phase Al' after extraction (in ppm).

[0184] With reference to Figure 9, which illustrates the Au(lll) extraction percentages obtained with the implementation of ZrÛ2-PEG2P-L functionalized particles 7 As mentioned above, it is observed that the extraction performance of the A2 phase constituted by these particles is close to 100%, or even equal to 100% for the functionalized ZrÛ2-PEG2P-L particles 7 in which the molar ratio ZrÛ2:PEG2P is 750:1.

[0185] Au(lll) Recovery

[0186] The Au(lll) which was extracted by the A2 phases is kept contained in the A2' phases.

[0187] After separation by centrifugation of the aqueous phases Al', the solid phases A2' were washed with 10 mL of water.

[0188] Au(lll) can be extracted from each of the phases A2' by contacting each of these phases A2' with an aqueous phase A3, thereby obtaining, after phase separation, a solid phase A2" and an aqueous phase A3' comprising Au(lll).

[0189] As an illustration, after extraction, the A2' phase obtained from the A2 phase formed by the functionalized ZrO2-PEG2P-L particles 7 of example 2 prepared according to route a and in which the ZrC2:PEG2P molar ratio is 1000:1 (the molar ratio always being ZrC2-PEG2P:L 7(50:1) was contacted with an aqueous phase A3 comprising 10 mL of 0.2 M thiourea and 10 mL of 0.5 M HCl for 4 h under stirring (300 rpm). The supernatant solution (aqueous phase A3') was then separated from the solid phase A2" by centrifugation at 10,000 rpm for 10 min.

[0190] The final concentrations of Au(lll) in the aqueous phase A3' were determined by measuring the distribution coefficients of the species in solution, by ICP-OES.

[0191] With reference to Figure 10, at the end of cycle 1 of extraction / de-extraction, we observe that the extracted Au(lll) has been almost completely de-extracted.

[0192] Recycling

[0193] At the end of cycle 1 of extraction / deextraction, three other cycles of extraction / deextraction, noted 2 to 4, were successively implemented.

[0194] With further reference to Figure 10, we observe that the extraction and de-extraction performance remains excellent.

[0195] For comparison, a first extraction and deextraction cycle followed by a second extraction and deextraction cycle were conducted according to the same operating protocol as described above, but using particles conforming to the teachings of publication [1]. Thus, instead of the functionalized ZrO2-PEG2P-L particles 7 These two extraction / deextraction cycles were conducted with ZrC particles functionalized with the ligand L 7 , denoted ZrC-L 7 , in a ZrC molar ratio :! 7 of 50:1.

[0196] Figure 11 shows that, if at the end of the first extraction / deextraction cycle, the implementation of ZrC-L particles 7allows to recover practically the Au(lll) initially contained in the aqueous phase Al, this is not the case at the end of the second extraction / deextraction cycle.

[0197] BIBLIOGRAPHY

[0198] [1] Publication by S. Asaad et al., “New Carbamoyl Surface-Modified ZrO2Nanohybrids for

[0199] Selective Au Extraction from E-Waste", Molecules, 2023, 28, 2219

Claims

Demands 1. Organic-inorganic hybrid material comprising bonded metal oxide particles (a) to at least one first compound corresponding to the following general formula (I): [H2O3P-Zp-(CH2) m -Z' q -(Y) n -(CH2) m -Zp-PO3H2] (I) in which - m represents an integer such that 0 < m < 50, - n represents an integer such that 0 < n < 100, - p represents an integer equal to 0 or 1, - q represents an integer equal to 0 or 1, at least one of which m, n, p and q is different from 0, - Y is chosen from the group consisting of CH2CH2O, CH2CH2 and CF2CF2, Y preferably being CH2CH2O, - Z is chosen from the group consisting of O, NH and CH2, and - Z' is O; and (b) to at least a second compound comprising an acid group, this second compound being an extractant of at least one metal M.

2. Organic-inorganic hybrid material according to claim 1, wherein n = p = q = 0, the first compound(s) corresponding to the following particular formula(s): [H2O3P-(CH2) 2m -PO3H2] (la) m being advantageously such that 2 < m < 35 and, preferably, such that 3 < m < 25.

3. Organic-inorganic hybrid material according to claim 1, wherein n * 0 and p = q = 0, the first compound(s) corresponding to the following particular formula (lb): [H2O3P-(CH2) m -(Y)n-(CH2) m -PO3H2] (lb) m being advantageously such that 1 < m < 4 and, preferably, such that 2 < m < 3 and n being advantageously such that 1 < n < 12 and, preferably, such that 2 < n < 10.

4. Organic-inorganic hybrid material according to claim 1, wherein n = q = 0 and p = 1, the first compound(s) corresponding to the following particular formula (lc): [H2O3P-Z-(CH2) 2m-Z-PO3H2] (lc) m being advantageously such that 1 < m < 20 and, preferably, such that 1 < m < 5.

5. Organic-inorganic hybrid material according to claim 1, wherein n * 0 and q = p = 1, the first compound(s) corresponding to the following particular formula (ld): [H2O3P-Z-(CH2) m -O-(Y) n -(CH2) m -Z-PO3H2] (ld) m being advantageously such that 1 < m < 4 and, preferably, such that 2 < m < 3 and n being advantageously such that 1 < n < 40 and, preferably, such that 2 < n < 20.

6. Organic-inorganic hybrid material according to claim 1, wherein n * 0, p = 0 and q = 1, the first compound(s) corresponding to the following particular formula(s): [H2O3P-(CH2) m -O-(Y) n -(CH2) m-PO3H2] (the) m being advantageously such that 1 < m < 4 and, preferably, such that 2 < m < 3 and n being able to be such that 20 < n < 80 and, in particular, such that 30 < n < 70, this first compound being advantageously α,co-bisphosphonic acid of poly(ethylene glycol) corresponding to the particular formula (the 1 ) next: [H2O3P-(CH2)3-O-(CH2CH2O) n -(CH2)3-PO3H2] (l-e') 7. Organic-inorganic hybrid material according to any one of claims 1, 3, 5 and 6, wherein, when n > 2, the Ys are identical.

8. Organic-inorganic hybrid material according to any one of claims 1 to 7, wherein the metal oxide is an oxide of a p-block or d-block metal, such metal oxide being advantageously chosen from the group consisting of ZrO2, TiO2, HfO2, ZnO, SnO2, Fe2O3, Al2O3 and Nb2O5 and being preferably ZrO2.

9. Organic-inorganic hybrid material according to any one of claims 1 to 8, wherein the metal oxide is in the form of particles having an average number size d5o of between 1 nm and 100 nm, advantageously between 3 nm and 50 nm and, preferably, between 5 nm and 15 nm.

10. Organic-inorganic hybrid material according to any one of claims 1 to 9, wherein the molar ratio between the metal oxide and the first compound, denoted metal oxide:first compound, is between 30000:1 and 200:1, advantageously between 20000:1 and 300:1 and, preferably, between 10000:1 and 500:

1.

11. Organic-inorganic hybrid material according to any one of claims 1 to 10, wherein the second compound is selected from the group consisting of phosphoric acids, phosphonic acids, carboxylic acids and sulfonic acids and is preferably a phosphoric acid or a phosphonic acid.

12. Organic-inorganic hybrid material according to any one of claims 1 to 11, wherein the second compound is a compound comprising a monocarbamoyl group or a dicarbamoyl group.

13. Organic-inorganic hybrid material according to any one of claims 1 to 12, wherein the molar ratio between the metal oxide and the second compound, denoted metal oxide:second compound, is between 500:1 and 10:1, advantageously between 200:1 and 20:1 and, preferably, between 100:1 and 50:

1.

14. A process for extracting one or more metals M selected from gold and platinum group metals contained in an aqueous phase Al comprising at least one step of contacting the aqueous phase Al with a phase A2, thereby obtaining, after a phase separation step, an aqueous phase Al' and a phase A2' comprising the metal(s) M, characterized in that the phase A2 comprises an organic-inorganic hybrid material according to any one of claims 1 to 13 as an extractant.

15. Extraction process according to claim 14, wherein phase A2 consists of an organic-inorganic hybrid material according to any one of claims 1 to 13 as an extractant.

16. A process for recovering one or more metals M selected from gold and platinum group metals contained in an aqueous phase Al, characterized in that it comprises the following successive steps (a) and (b): (a) the extraction of the metal(s) M from the acidic aqueous phase Al by an extraction process according to claim 14 or 15; and (b) the removal of the metal(s) M present in phase A2' as obtained at the end of step (a), thereby obtaining a phase A2" from which the metal(s) M have been removed.

17. A recovery method according to claim 16 comprising, further, after step (b), at least one additional cycle comprising steps (b 1 ) and (b") following successive: (b 1 ) the extraction of the metal(s) M comprising at least one step of contacting the aqueous phase Al with the phase A2" as obtained at the end of step (b), thereby obtaining, after a phase separation step, an aqueous phase Al" and a phase A2" comprising the metal(s) M; and (b") the extraction of the metal(s) M present in phase A2'" as obtained at the end of step (b 1 ).

18. Extraction process according to claim 14 or 15 or recovery process according to claim 16 or 17, characterized in that the aqueous phase Al is a solution resulting from the acid attack of a natural ore or an urban mine comprising said metal(s) M.

19. Extraction or recovery process according to claim 18, wherein the aqueous phase Al has a total molar concentration of metals M of at least 0.01 ppm, in particular between 0.01 ppm and 200 ppm, advantageously between 0.1 ppm and 100 ppm and preferably between 0.1 ppm and 50 ppm.

20. Extraction or recovery process according to claim 18 or 19, wherein the metal(s) M are selected from gold and platinum group metals, advantageously from gold and palladium, the metal M being, preferably, gold.

21. Organic-inorganic hybrid material comprising metal oxide particles bonded to at least one first compound corresponding to the following general formula (I): [H2O3P-Zp-(CH2) m -Z' q -(Y) n -(CH2) m -Zp-PO3H2] (I) in which - m represents an integer such that 0 < m < 50, - n represents an integer such that 0 < n < 100, - p represents an integer equal to 0 or 1, - q represents an integer equal to 0 or 1, with at least two among m, n, p and q being different from 0, - Y is chosen from the group consisting of CH2CH2O, CH2CH2 and CF2CF2, Y being preferably CH2CH2O, except when p = q = 0 in which case Y is CH2CH2O OR CF2CF2, preferably CH2CH2O, - Z is chosen from the group consisting of O and NH, and - Z 1 is O.

22. Organic-inorganic hybrid material according to claim 21, wherein n * 0 and p = q = 0, the first compound(s) corresponding to the following particular formula (lb): [H2O3P-(CH2) m -(Y) n -(CH2) m -PO3H2] (lb) m being advantageously such that 1 < m < 4 and, preferably, such that 2 < m < 3 and n being advantageously such that 1 < n < 12 and, preferably, such that 2 < n < 10.

23. Organic-inorganic hybrid material according to claim 21, wherein n = q = 0 and p = 1, the first compound(s) corresponding to the following particular formula (lc): [H2O3P-Z-(CH2) 2m-Z-PO3H2] (lc) m being advantageously such that 1 < m < 20 and, preferably, such that 1 < m < 5.

24. Organic-inorganic hybrid material according to claim 21, wherein n * 0 and q = p = 1, the first compound(s) corresponding to the following particular formula (ld): [H2O3P-Z-(CH2) m -O-(Y) n -(CH2) m -Z-PO3H2] (ld) m being advantageously such that 1 < m < 4 and, preferably, such that 2 < m < 3 and n being advantageously such that 1 < n < 40 and, preferably, such that 2 < n < 20.

25. Organic-inorganic hybrid material according to claim 21, wherein n * 0, p = 0 and q = 1, the first compound(s) corresponding to the following particular formula(s): [H2O3P-(CH2) m -O-(Y) n -(CH2) m-PO3H2] (the) m being advantageously such that 1 < m < 4 and, preferably, such that 2 < m < 3 and n being able to be such that 20 < n < 80 and, in particular, such that 30 < n < 70, this first compound being advantageously α,co-bisphosphonic acid of poly(ethylene glycol) corresponding to the particular formula (the 1 ) next: [H2O3P-(CH2)3-O-(CH2CH2O)n-(CH2)3-PO3H2] (l-e') 26. Organic-inorganic hybrid material according to any one of claims 21, 22, 24 and 25 in which, when n > 2, the Y are identical.

27. Organic-inorganic hybrid material according to any one of claims 21 to 26, wherein the metal oxide is an oxide of a p-block or d-block metal, such metal oxide being advantageously chosen from the group consisting of ZrO2, TiO2, HfO2, ZnO, SnO2, Fe2O3, Al2O3 and Nb2O5 and being preferably ZrO2.

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