Amino acid-derived adsorbents and uses thereof for metal ion separation

Abstract

A metal-based nanostructure produced from an amino acid-based supramolecular framework compound. A method using the metal-based nanostructure to separate copper or nickel ions from a solution comprising at least one of copper or nickel ions. A transition metal material comprising the copper and / or nickel ions with the metal-based nanostructure.

Description

AMINO ACID-DERIVED ADSORBENTS AND USES THEREOF FOR METAL ION SEPARATIONSTATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT

[0001] N / ACROSS-REFERENCE TO RELATED APPLICATIONS

[0002] The present patent application claims priority under 35 U.S.C. 119(e) to the U.S provisional patent application identified as U.S. Serial No. 63 / 604,129, filed on November 29, 2023, which is hereby incorporated by reference herein in its entirety.BACKGROUND

[0003] Selective separation of given target metal ions from mixtures of ions with similar ionic properties (such as those among the same metal groups) has been a challenging component of critical material recovery and concomitant water remediation. The development of innovative separation technologies by increasing the selectivity among similar metal ions has the potential to produce sustainable and environmentally-friendly ionic separation processes for resource recovery and water reuse. It is to achieving this goal that the present disclosure is directed.BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Several embodiments of the present disclosure are hereby illustrated in the appended drawings. It is to be noted however, that the appended drawings only illustrate several typical embodiments and are therefore not intended to be considered limiting of the scope of the inventive concepts disclosed herein.

[0005] FIG. 1 is a schematic illustration of presently disclosed amino acid-based supramolccular framework (aaSCC) adsorbents, and their use in separation of copper and nickel ions in wastewater by adsorbing the Cu2+ions while substantially not adsorbing the Ni2+ions.

[0006] FIG. 2 shows synthetic reactions of aaSCC adsorbents made with the amino acid enantiomers L-Methionine (1), D-Methionine (2), DL-Methionine (3), L-Phenylalanine (4) and D-Phenylalanine (5), and scanning electron microscopy (SEM) images which show the morphology of the resulting aaSCC adsorbents.

[0007] FIG. 3 shows synthetic reactions of aaSCC adsorbents made with the amino acid enantiomers L-Lysine (6), L-Cysteine (7), L-Histidine (8), and L-Glutamic acid (9), and scanning electron microscopy (SEM) images which show the morphology of the resulting aaSCC adsorbents.

[0008] FIG. 4 shows synthetic reactions of aaSCC adsorbents made with the amino acid enantiomers L-Aspailic acid (10), Taurine (11), L-Arginine (12) and L-Tryptophan (13), and scanning electron microscopy (SEM) images which show the morphology of the resulting aaSCC adsorbents.

[0009] FIG. 5 shows Cu2+ / Ni2+separation factors of the aaSCC adsorbents when exposed to aqueous solutions (pH = 2.5 and 5) simultaneously containing equimolar (10 ppm) of Cu2+and Ni2+.

[0010] FIG. 6 shows Cu2+ / Ni2+separation factors of aaSCC adsorbents when exposed to aqueous solutions (pH = 2.5 and 5) simultaneously containing equimolar concentration (200 ppm) of Cu2+and Ni2+.

[0011] FIG. 7 shows adsorption results of the aaSCC adsorbents when exposed to aqueous solutions (pH = 2.5 and 5) simultaneously containing equimolar (10 ppm) of Cu2+and Ni2+.

[0012] FIG. 8A shows the adsorption efficiencies (%) of the aaSCC adsorbents when exposed to aqueous solutions (pH = 2.5 and 5) simultaneously containing equimolar concentration (200 ppm) of Cu2+and Ni2+.

[0013] FIG. 8B shows the adsorption capacities (mg / g) of the aaSCC adsorbents when exposed to aqueous solutions (pH = 2.5 and 5) simultaneously containing equimolar concentration (200 ppm) of Cu2+and Ni2+. Numbering is l=D-methionine, 2=D-methionine, 3=DE-methionine, 4=E- phenylalanine, 5=D-phenylalanine, 6=E-lysine, 7=E-cysteine, 8=E-histidine, 9=E-glutamic acid, 10=E-aspartic acid, l l=taurine, 12-L-argininc, and 13=E-tryptophan.DETAILED DESCRIPTION

[0014] The present disclosure is directed to methods in which amino acids arc used as coligands with a metal salt and an oxime ligand to synthesize amino acid-based supramolecular framework adsorbents, also referred to herein as amino acid-based supramolecular coordination complex (aaSCC) adsorbents, i.e., aaSCC adsorbents, which can be used for example for selective separation of Cu2+and Ni2+ions in wastewaters (FIG. 1).

[0015] Before further describing various embodiments of the present disclosure in more detail by way of exemplary description, examples, and results, it is to be understood that the compounds, compositions, and methods of present disclosure are not limited in application to the details of specific embodiments and examples as set forth in the following description. The description provided herein is intended for purposes of illustration only and is not intended to be construed in a limiting sense. As such, the language used herein is intended to be given the broadest possible scope and meaning, and the embodiments and examples are meant to be exemplary, not exhaustive. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description only and should not be regarded as limiting unless otherwise indicated as so. In the description below, numerous specific details are set forth in order to provide a more thorough understanding of the present disclosure. However, it will be apparent to a person having ordinary skill in the art that the present disclosure may be practiced without these specific details. In other instances, features which are well known to persons of ordinary skill in the art have not been described in detail to avoid unnecessary complication of the description. It is intended that all alternatives, substitutions, modifications, and equivalents apparent to those having ordinary skill in the art are included within the scope of the present disclosure. Thus, while the compounds, compositions, and methods of the present disclosure have been described in terms of particular embodiments, it will be apparent to those of skill in the art that variations may be applied to the compounds, compositions, and methods and in the steps or in the sequence of steps of the methods described herein without departing from the concept, spirit, and scope of the inventive concepts.

[0016] Each patent, published patent application, and non-patent publication referenced in any portion of this application, including U.S. Provisional Patent Application No. 63 / 517,297, is expressly incorporated herein by reference in its entirety to the same extent as if the individual patent, or published patent application, or non-patent publication was specifically and individually indicated to be incorporated by reference.

[0017] Unless otherwise defined herein, scientific and technical terms used in connection with the present disclosure shall have the meanings that arc commonly understood by those having ordinary skill in the art. Further, unless otherwise required by context, singular terms shall include pluralities and plural terms shall include the singular.

[0018] The following abbreviations may be used herein:A: Angstrom, aaSCC: amino acid-based supramolecular framework,°C: degrees Celsius,Co: Cobalt,Co2+: Cobalt ion,Cu: Copper,Cu2+: Copper ion,DI: distilled, h: hour,ICP-OES: Inductively coupled plasma optical emission spectroscopy,KOH: Potassium hydroxide,M: Molar, mg: milligram, mL: milliliter, mm: millimeter,Mn: Manganese,Mn2+: Manganese ion, pm: micrometer,NaOH: Sodium hydroxide,Ni: Nickel,Ni2+: Nickel ion, ppm: parts per million, rpm: revolutions per minute,SEM: scanning electron microscopy, wt%: weight percent, Zn: Zinc,Zn2+: Zinc ion.

[0019] As utilized in accordance with the methods and compositions of the present disclosure, the following terms, unless otherwise indicated, shall be understood to have the following meanings:

[0020] The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and / or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” The use of the term “or” in the claims is used to mean “and / or” unless explicitly indicated to refer to alternatives only or when the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and / or.” The use of the term “at least one” will be understood to include one as well as any quantity more than one, including but not limited to, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 30, 40, 50, 100, or any integer inclusive therein. The term “at least one” may extend up to 100 or 1000 or more, depending on the term to which it is attached; in addition, the quantities of 100 / 1000 are not to be considered limiting, as higher limits may also produce satisfactory results. In addition, the use of the term “at least one of X, Y and Z” will be understood to include X alone, Y alone, and Z alone, as well as any combination of X, Y and Z. The term “plurality” refers to two or more items. Where used herein, the specific term “single” is limited to only “one,” and a “pair” means two.

[0021] As used herein, all numerical values or ranges include fractions of the values and integers within such ranges and fractions of the integers within such ranges unless the context clearly indicates otherwise. Thus, to illustrate, reference to a numerical range, such as 1-10 includes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, as well as 1.1, 1.2, 1.3, 1.4, 1.5, etc., and so forth. Reference to a range of 1-50 therefore includes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, etc., up to and including 50, as well as 1.1, 1.2, 1.3, 1.4, 1.5, etc., 2.1, 2.2, 2.3, 2.4, 2.5, etc., and so forth. Reference to a series of ranges includes ranges which combine the values of the boundaries of different ranges within the series. Thus, to illustrate reference to a series of ranges, for example, of 1-10, 10-20, 20-30, 30-40, 40-50, 50-60, 60-75, 75-100, 100-150, 150-200, 200- 250, 250-300, 300-400, 400-500, 500-750, 750-1,000, includes ranges of 1-20, 10-50, 50-100, 100-500, and 500-1,000, for example.

[0022] As noted above, any numerical range listed or described herein is intended to include, implicitly or explicitly, any number or sub-range within the range, particularly all integers,including the end points, and is to be considered as having been so stated. For example, "a range from 1.0 to 10.0" is to be read as indicating each possible number, including integers and fractions, along the continuum between and including 1.0 and 10.0, that is, having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, for example, 3.25 to 8.65. Any maximum numerical limitation recited herein is intended to include all lower numerical limitations subsumed therein, and any minimum numerical limitation recited in this specification is intended to include all higher numerical limitations subsumed therein. Accordingly, Applicant reserves the right to amend this specification, including the claims, to expressly recite any sub-range subsumed within the ranges expressly recited herein. Thus, even if a particular data point within the range is not explicitly identified or specifically referred to, it is to be understood that any data points within the range are to be considered to have been specified, and that the inventor(s) possessed knowledge of the entire range and the points within the range.

[0023] As used in this specification and claims, the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open- ended and do not exclude additional, unrecited elements or method steps.

[0024] The term “or combinations thereof’ as used herein refers to all permutations and combinations of the listed items preceding the term. For example, “A, B, C, or combinations thereof’ is intended to include at least one of: A, B, C, AB, AC, BC, or ABC, and if order is important in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, expressly included are combinations that contain repeats of one or more item or term, such as BB, AAA, AAB, BBC, AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan will understand that typically there is no limit on the number of items or terms in any combination, unless otherwise apparent from the context.

[0025] Throughout this application, the terms “about” or “approximately” are used to indicate that a value includes the inherent variation of error for the composition, the method used to administer the composition, or the variation that exists among the study subjects. As used herein the qualifiers “about” or “approximately” are intended to include not only the exact value, amount, degree, orientation, or other qualified characteristic or value, but are intended to include some slight variations due to measuring error, manufacturing tolerances, observer error, andcombinations thereof, for example. The term “about” or “approximately”, where used herein when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass, for example, variations of ± 20% or ± 10%, or ± 5%, or ± 1%, or ± 0.1% from the specified value, as such variations are appropriate to perform the disclosed methods and as understood by persons having ordinary skill in the art. As used herein, the term “substantially” means that the subsequently described event or circumstance completely occurs or that the subsequently described event or circumstance occurs to a great extent or degree. For example, the term “substantially” means that the subsequently described event or circumstance occurs at least 80% of the time, at least 90% of the time, at least 91% of the time, at least 92% of the time, at least 93% of the time, at least 94% of the time, at least 95% of the time, at least 96% of the time, at least 97% of the time, at least 98% of the time, or at least 99% of the time.

[0026] As used herein any reference to “one embodiment” or “an embodiment” means that a particular element, feature, composition, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment.

[0027] Where used herein, the pronoun “we” is intended to refer to all persons involved in a particular aspect of the investigation disclosed herein and as such may include non-inventor laboratory assistants and non-inventor collaborators working under the supervision of the inventor(s).

[0028] The term “wt%” (a.k.a., “wt / wt%” and “%(w / w)”) when used in reference to a solute is a measure of the concentration of a solute in a solution in terms of the mass of the solute and the mass of the solvent in which the solute is dissolved. The solutemass + the solventmass = the solutionmass. Wt% is calculated by dividing the solutemass by the solutionmass, then multiplying the resulting quotient by 100.

[0029] The term “substrate” may also be used interchangeably herein with the term “membrane support.”

[0030] Where reference is made herein to a step of “passing the aqueous solution across the metal-based nanostructure,” it is intended to refer to a step in which an aqueous solution is passed over a stationary substrate comprising the metal based nanostructures, or is passed across a membrane interface having the aaSCC adsorbent acting as an active layer, or is passed through apacked-bed column or container holding the metal-based nanostructures, or wherein a quantity of the metal based nanostructure is mixed with an aqueous solution then separated therefrom. Thus the step is not to be limited to passing an aqueous solution over or through a stationary mass of the metal-based nanostructures.

[0031] Methods of preparing the materials and their selective separation behavior towards copper and nickel ions are disclosed herein. In certain non-limiting embodiments, the methods for synthesizing aaSCC adsorbents used amino acids including, but not limited to, L-Lysine, L- Cysteine, L-Histidine, L-Glutamic acid, L-Aspartic acid, L- Arginine, Taurine, and L-Tryptophan. Different crystal structures were formed, with a three-dimensional flower-like structure being the dominant nanostructural form. Second, chirality effects controlled by employing appropriate D- enantiomers, L- enantiomers, or DL-enantiomers into the aaSCC adsorbents affected the selective ion capture behavior, especially, in the case of methionine, and D- / L-phenylalanine case shows a legible difference. Third, the aaSCC adsorbents display distinct Cu2+ / Ni2+separation behaviors (e.g., adsorption capacity, efficiency, and Cu2+ / Ni2+separation factor at different initial ionic concentration ranges) when different amino acids are employed. Any D-amino acid and / or L- amino acid which functions in accordance with the present disclosure can be used to form an aaSCC adsorbent for use in the methods described herein, including but not limited to glycine, and D- and / or L- isomers of arginine, aspartic acid, cysteine, glutamic acid, histidine, lysine, methionine, phenylalanine, taurine, tryptophan, serine, threonine, asparagine, glutamine, proline, alanine, valine, leucine, isoleucine, tyrosine, N-acetyl-L-cysteine, and glutathione. Fourth, we hypothesize that aaSCC adsorbents can be utilized to separate various pairs of metal ions, including but not limited to Cu2+ / Mn2+, Cu2+ / Co2+, or mixtures of Cu2+ / Ni2+ / Mn2+ / Co2+.

[0032] Demonstrated herein are facile and green (environmentally-friendly) synthetic methods for preparing bioinspired metal ion adsorbents (aaSCC adsorbents) by incorporating natural amino acids as co-ligands. The design space spans (but is not limited to) at least 13 chemically and structurally diverse amino acids. The presently disclosed aaSCC adsorbents show remarkable selectivity between Cu2+and Ni2+in different ionic concentration ranges. The present work demonstrates that the disclosed aaSCC adsorbents offer a new and sustainable paradigm for the development and deployment of advanced materials effective for selective ion detection, capture, and / or removal from diverse water tables, which can be used in improved processes for resource recovery and water reuse.

[0033] Certain novel embodiments of the present disclosure, having now been generally described, will be more readily understood by reference to the following examples, which arc included merely for purposes of illustration of certain aspects and embodiments of the present disclosure, and are not intended to be limiting. The following examples are to be construed, as noted above, only as illustrative, and not as limiting of the present disclosure in any way whatsoever. Those skilled in the art will promptly recognize appropriate variations from the various compositions, structures, components, procedures and methods.METHODSFabrication of zinc-based aaSCC adsorbents

[0034] Compound (1) was synthesized by mixing a zinc salt, such as Zn(NO3)2.6H2O, salicylaldoxime ligand, L-methionine co-ligand, and NaOH or other bases such as KOH (e.g., at a molarity of 0.05M) in a 1 :6:8 :2 ratio in a glass bottle at room temperature, followed by heating the tightly sealed bottle to 55 °C and maintaining the reaction mixture at this temperature for 24 hours. The resulting white product was then washed with DI water, dried under vacuum overnight, and identified as compound (1).

[0035] Similar zinc-based aaSCCs were synthesized using the same method, but with different amino acid co-ligands and Zn2+: salicylaldoxime : amino acid : NaOH ratios. Specifically, compounds (2) to (13) were synthesized using D-methionine (1 :6:8:2), DL-methionine (1 :6:8:2), L-phenylalanine (1 :6:8:2), D-phenylalanine (1:6:8:2), L-lysine (1 :6:8:2), L-cysteine (3:2: 1 :2), L- histidine (3:2:1:2), L-glutamic acid (3:2:1:2), L-aspartic acid (1:2:1:2), taurine (1:6:8:2), L- arginine (1:6:8:2), and L-tryptophan (1 :6:8:2) (FIGS. 2-4).Selective adsorption experimental apparatus

[0036] The initial concentration of ions in a solution is a factor in determining the success of an adsorbent in selectively capturing and separating those ions. To assess the ability of the aaSCC- adsorbents to adsorb and separate Cu2+from a mixture with Ni2+, we prepared equimolar solutions of these two ions at 10 ppm and 200 ppm at different pH conditions (pH 2.5, and pH 5). aaSCC adsorbents can effectively treat a wide range of contaminant ion concentrations, spanning from, for example, 0.01 ppm to 750 ppm. The pH of the aqueous solution was adjusted using a 0.1M solution of HC1. Any other appropriate acid could be used to adjust the pH.

[0037] For a 10 ppm initial concentration, a glass vial containing 2.5 mg of the adsorbent was filled with a 10 mL aqueous solution of Cu and Ni ions at concentrations of approximately 10 ppm. The mixture was then agitated using a roller shaker at 55 rpm and room temperature for a duration of 4 hours. Afterwards, the mixture was centrifuged at 8000 rpm for 5 minutes to separate the solid adsorbent from the liquid supernatant, which was then filtered through a 0.22 pm membrane filter to obtain a clear solution. Finally, the concentration of Cu and Ni ions in the solution was measured using ICP-OES to evaluate the adsorption performance of the adsorbents.

[0038] For a 200 ppm initial concentration, a 3 mL aqueous solution containing approximately 200 ppm of Cu and Ni ions was added to a glass vial containing 2.5 mg of the adsorbent. The mixture was agitated for 4 hours at room temperature using a roller shaker operating at 55 rpm to ensure sufficient adsorption. The mixture was then subjected to centrifugation at 8000 rpm for 5 minutes to separate the solid adsorbent from the liquid solution. The clear solution was obtained by filtering the liquid through a 0.22 pm membrane filter to remove any residual adsorbent. Finally, the concentration of Cu and Ni ions in the solution was measured using ICP-OES to evaluate the effectiveness of the adsorbents (FIGS. 5-8B).

[0039] Examples of zinc salts that can be used to make the compounds of the present disclosure include but are not limited to zinc nitrate (Zn(NO.i)2), zinc acetate (Zn(OAc)2), zinc chloride (ZnCh), zinc sulfate (ZnSO4), and zinc acetylacetonate (Zn(CsH7O2)2).

[0040] Examples of amino acid ligands that can be used in the methods of the present disclosure include but are not limited to glycine, D- and L-alanine, D- and L-arginine, D- and L- asparagine, D- and L-aspartic acid, D- and L-cysteine, D- and L-glutamine, D- and L-glutamic acid, D- and L-histidine, D- and L-isoleucine, D- and L-leucine, D- and L-lysine, D- and L-methionine, D- and L-phenylalanine, D- and L-proline, D- and L-serine, D- and L-threonine, D- and L-tryptophan, D- and L-tyrosine, D- and L-valine, D- and L-taurine, D- and L-N-acetyl-L-cysteine, and D- and L- glutathione.

[0100] Examples of oxime ligands that can be used to make the compounds of the present disclosure include, but are not limited to, salicylaldoxime, benzaldehyde oxime, acetophenone oxime, cyclohexanone oxime, a-Benzoin oxime, 4-pyridinecarb aldehyde oxime, 2- pyridinecarbaldehyde oxime, 5 -methoxy nicotinaldehy de oxime, 5,6-dimethoxypicolinaldehyde oxime, 3,4,5-trimethoxybenzaldehyde oxime, benzamide oxime, 4-methylbenzamide oxime, 4- aminobenzamide oxime, and 2-chlorobenzaldehyde oxime.

[0101] Thus, in accordance with the present disclosure, there have been provided compounds and compositions, as well as methods of producing and using same, which fully satisfy the objectives and advantages set forth hereinabove. Although the present disclosure has been described in conjunction with specific formulas, compounds, compositions, and methods set forth hereinabove, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications, and variations that fall within the spirit and broad scope of the present disclosure.

[0041] Accordingly, the present disclosure is directed to at least the following non-limiting embodiments:

[0042] Clause 1. A metal-based nanostructure produced by a method comprising the steps of (1) providing a first aqueous solution comprising an oxime ligand, a second aqueous solution comprising an amino acid, a third aqueous solution comprising a metal salt, and a fourth aqueous solution comprising a base, (2) combining and mixing the first aqueous solution and the second aqueous solution to form a first mixture, (3) combining and mixing the first mixture with the third aqueous solution to form a second mixture, (4) combining the second mixture with the fourth aqueous solution to form a reaction mixture in a sealed container, (5) heating the reaction mixture in the sealed container to a predetermined elevated temperature and maintaining the reaction mixture at the elevated for a predetermined period, wherein the reaction mixture forms an amino acid-based supramolecular framework compound which precipitates into the metal-based nanostructure, and (6) purifying the metal-based nanostructure.

[0043] Clause 2. The metal-based nanostructure of clause 1, wherein the oxime ligand is selected from the group consisting of salicylaldoxime, benzaldehyde oxime, acetophenone oxime, cyclohexanone oxime, a-Benzoin oxime, 4-pyridinecarbaldehyde oxime, 2-pyridinecarbaldehyde oxime, 5-methoxynicotinaldehyde oxime, 5,6-dimethoxypicolinaldehyde oxime, 3,4,5- trimethoxybenzaldehyde oxime, benzamide oxime, 4-methylbenzamide oxime, 4- aminobenzamide oxime, and 2-chlorobenzaldehyde oxime.

[0044] Clause 3. The metal-based nanostructure of either clause 1 or 2, wherein the amino acid is selected from the group consisting of glycine, D- and L-arginine, D- and L-aspartic acid, D- and L-cysteine, D- and L-glutamic acid, D- and L-histidine, D- and L-lysine, D- and L- methionine, D- and L-phenylalanine, D- and L-taurine, D- and L-tryp(ophan, D- and L-serine, D- and L-threonine, D- and L- asparagine, D- and L- glutamine, D- and L- proline, D- and L- alanine,D- and L- valine, D- and L- leucine, D- and L- isoleucine, D- and L- tyrosine, D- and L- N-acetyl- L-cystcinc, and D- and L- glutathione.

[0045] Clause 4. The metal-based nanostructure of any one of clauses 1-3, wherein the metal salt is a zinc salt.

[0046] Clause 5. The metal-based nanostructure of any one of clauses 1-4, wherein the metal salt is a zinc salt selected from the group consisting of zinc nitrate (Zn(NOs)2), zinc acetate (Zn(OAc)2), zinc chloride (ZnCh), zinc sulfate (ZnSC ), and zinc acetylacetonate ('ZniCsHvChh).

[0047] Clause 6. The metal-based nanostructure of any one of clauses 1-5, wherein the base is NaOH.

[0048] Clause 7. The metal-based nanostructure of any one of clauses 1-6, wherein the oxime ligand, the amino acid, the metal salt, and the base are provided in an oxime ligand:amino acid:metal salt:base ratio selected from 1 :6:8:2, 3:2:1:2, and 1 :2: 1 :2.

[0049] Clause 8. The metal-based nanostructure of any one of clauses 1-7, wherein the predetermined elevated temperature is in a range of about 30°C to about 65°C.

[0050] Clause 9. The metal-based nanostructure of any one of clauses 1-8, wherein the predetermined elevated temperature is in a range of about 50°C to about 60°C.

[0051] Clause 10. The metal-based nanostructure of any one of clauses 1-9, wherein the predetermined period is in a range of about 2 to about 36 hours.

[0052] Clause 11. The metal-based nanostructure of any one of clauses 1-10, wherein the predetermined elevated temperature is about 55°C ± 1°C and the predetermined period is about 24

[0053] Clause 12. A method of purifying a transition metal ion, comprising, (1) providing a transition metal ion-containing aqueous solution comprising a first transition metal ion selected from copper and nickel, and at least one second type of transition metal ion, (2) providing the metal-based nanostructure of any one of clauses 1-9, and (3) passing the aqueous solution across the metal-based nanostructure, wherein the first type of transition metal ion is adsorbed preferentially onto the metal-based nanostructure as compared to the at least one second type of transition metal ion, thereby reducing the concentration of the first type of transition metal ion in the aqueous solution.

[0054] Clause 13. The method of clause 12, wherein the metal-based nanostructure is adhered to or disposed on a solid support structure.

[0055] Clause 14. The method of either clause 12 or 13, wherein the metal-based nanostructure is contained within a column or container.

[0056] Clause 15. The method of any one of clauses 12-14, wherein the aqueous solution comprises at least one of wastewater, brine, and mine drainage.

[0057] Clause 16. The method of any one of clauses 12-15, wherein the aqueous solution has a pH in a range of about 2.5 to about 8.

[0058] Clause 17. The method of any one of clauses 12-16, wherein the at least one second type of transition metal ion is selected from the group consisting of Cu, Ni, Mn, and Co ions, with the proviso that the second type of transition metal ion is different from the first type of transition metal ion.

[0059] Clause 18. The method of any one of clauses 12-17, wherein the first type of transition metal ion is Cu2+and the at least one second type of transition metal ion is Ni2+.

[0060] Clause 19. A transition metal material, comprising at least one of Cu and Ni and at least one second type of transition metal ion complexed with the metal-based nanostructure of any one of clauses 1-11, wherein the at least one second type of transition metal ion is selected from the group consisting of Cu, Ni, Mn, and Co ions, with the proviso that the second type of transition metal ion is different from the first type of transition metal ion.

[0061] While the present disclosure has been described herein in connection with certain embodiments so that aspects thereof may be more fully understood and appreciated, it is not intended that the present disclosure be limited to these particular embodiments. On the contrary, it is intended that all alternatives, modifications and equivalents are included within the scope of the present disclosure as defined herein. Thus the examples described above, which include particular embodiments, will serve to illustrate the practice of the inventive concepts of the present disclosure, it being understood that the particulars shown are by way of example and for purposes of illustrative discussion of particular embodiments only and are presented in the cause of providing what is believed to be the most useful and readily understood description of procedures as well as of the principles and conceptual aspects of the present disclosure. Changes may be made in the formulation of the various compositions described herein, the methods described herein or in the steps or the sequence of steps of the methods described herein without departing from the spirit and scope of the present disclosure. Further, while various embodiments of the presentdisclosure have been described in claims herein below, it is not intended that the present disclosure be limited to these particular claims.

Claims

What is claimed is:

1. A metal-based nanostructure produced by the method comprising: providing a first aqueous solution comprising an oxime ligand, a second aqueous solution comprising an amino acid, a third aqueous solution comprising a metal salt, and a fourth aqueous solution comprising a base; combining and mixing the first aqueous solution and the second aqueous solution to form a first mixture; combining and mixing the first mixture with the third aqueous solution to form a second mixture; combining the second mixture with the fourth aqueous solution to form a reaction mixture in a sealed container; heating the reaction mixture in the sealed container to a predetermined elevated temperature and maintaining the reaction mixture at the elevated for a predetermined period, wherein the reaction mixture forms an amino acid-bascd supramolccular framework compound which precipitates into the metal-based nanostructure; and purifying the metal-based nanostructure.

2. The metal-based nanostructure of claim 1, wherein the oxime ligand is selected from the group consisting of salicylaldoxime, benzaldehyde oxime, acetophenone oxime, cyclohexanone oxime, a-Benzoin oxime, 4-pyridinecarbaldehyde oxime, 2-pyridinecarbaldehyde oxime, 5- methoxynicotinaldehyde oxime, 5,6-dimethoxypicolinaldehyde oxime, 3,4,5- trimethoxybenzaldehyde oxime, benzamide oxime, 4-methylbenzamide oxime, 4- aminobenzamide oxime, and 2-chlorobenzaldehyde oxime.

3. The metal-based nanostructure of claim 1, wherein the amino acid is selected from the group consisting of glycine, D- and L-arginine, D- and L-aspartic acid, D- and L-cysteine, D- and L-glutamic acid, D- and L-histidine, D- and L-lysine, D- and L-methionine, D- and L- phenylalanine, D- and L-taurine, D- and L-tryptophan, D- and L-serine, D- and L-threonine, D- and L- asparagine, D- and L- glutamine, D- and L- proline, D- and L- alanine, D- and L- valine,D- and L- leucine, D- and L- isoleucine, D- and L- tyrosine, D- and L- N-acetyl-L-cysteine, and D- and L- glutathione.

4. The metal-based nanostructure of claim 1, wherein the metal salt is a zinc salt.

5. The metal-based nanostructure of claim 4, wherein the zinc salt is selected from the group consisting of zinc nitrate (Zn(N03) ), zinc acetate (Zn(OAc)o), zinc chloride (ZnCh), zinc sulfate (Z11SO4), and zinc acetylacetonate (ZnCCstbC ).

6. The metal-based nanostructure of claim 1, wherein the base is NaOH.

7. The metal-based nanostructure of claim 1, wherein the oxime ligand, the amino acid, the metal salt, and the base are provided in an oxime ligand:amino acid:metal salt:base ratio selected from 1:6:8:2, 3:2:1:2, and 1:2: 1:2.

8. The metal-based nanostructure of claim 1 , wherein the predetermined elevated temperature is in a range of about 30°C to about 65 °C.

9. The metal-based nanostructure of claim 8, wherein the predetermined elevated temperature is in a range of about 50°C to about 60°C.

10. The metal-based nanostructure of claim 1, wherein the predetermined period is in a range of about 2 h to about 36 h.

11. The metal-based nanostructure of claim 1 , wherein the predetermined elevated temperature is about 55°C ± 1°C and the predetermined period is about 24 h ± 1 h.

12. A transition metal material, comprising at least one of Cu and Ni and at least one second type of transition metal ion complexed with the metal-based nanostructure of any one of claims 1- 11, wherein the at least one second type of transition metal ion is selected from the group consistingof Cu, Ni, Mn, and Co ions, with the proviso that the second type of transition metal ion is different from the first type of transition metal ion.

13. A method of purifying a transition metal ion, comprising; providing a transition metal ion-containing aqueous solution comprising a first transition metal ion selected from copper and nickel, and at least one second type of transition metal ion; providing the metal-based nanostructure of any one of claims 1-11; and passing the aqueous solution across the metal-based nanostructure, wherein the first type of transition metal ion is adsorbed preferentially onto the metal-based nanostructure as compared to the at least one second type of transition metal ion, thereby reducing the concentration of the first type of transition metal ion in the aqueous solution.

14. The method of claim 13, wherein the metal-based nanostructure is adhered to or disposed on a solid support structure.

15. The method of claim 13, wherein the metal-based nanostructure is contained within a column or container.

16. The method of claim 13, wherein the aqueous solution comprises at least one of wastewater, brine, and mine drainage.

17. The method of claim 13, wherein the aqueous solution has a pH in a range of about 2.5 to about 8.

18. The method of claim 13, wherein the at least one second type of transition metal ion is selected from the group consisting of Cu, Ni, Mn, and Co ions, with the proviso that the second type of transition metal ion is different from the first type of transition metal ion.

19. The method of claim 13, wherein the first type of transition metal ion is Cu2+and the at least one second type of transition metal ion is Ni2+.

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