Chelating polymer for recovery from seawater and brine

Abstract

Systems and methods of separating a metal ion from an aqueous solution comprising the metal ion include contacting the aqueous solution with a polymer. Contacting the aqueous solution with the polymer may include passing the aqueous solution through a packed bed column comprising the polymer. The aqueous solution may include about 0.5 wt.% to about 26 wt.% sodium chloride, and the metal ion includes silver, copper, zinc, nickel, or a combination of any two or more thereof.

Description

Atty. Dkt. No. 046434-0971CHELATING POLYMER FOR RECOVERY FROM SEAWATER AND BRINETECHNICAL FIELD

[0001] The present application claims priority to U.S. Provisional Patent App. No. 63 / 735,262 filed on December 17, 2024, the disclosure of which is incorporated herein by reference in its entirety for all purposes.TECHNICAL FIELD

[0002] The present technology is generally related to systems and methods of separating metal ions from an aqueous solution using a packed bed column. Specifically, the metal ions include silver, copper, zinc, nickel, or a combination of any two or more thereof.BACKGROUND

[0003] Water scarcity is a pressing global issue, with millions of people struggling to access clean and reliable freshwater sources. Desalination, the process of removing salt and other impurities from seawater to make it drinkable, is a technique that has been developed to address the problem of water scarcity. As traditional freshwater sources become scarcer, desalination offers a way to provide water where freshwater is scarce. However, while desalination can help alleviate water shortages, it comes with challenges, including concerns related to disposal of the brine formed as a byproduct of the desalination process.

[0004] Desalination processes include, but are not limited to, reverse osmosis (RO), distillation, electrodialysis, and capacitive deionization (CDI).

[0005] RO, one of the more common processes, is a water purification process that uses a semi-permeable membrane to separate impurities, including salts, from water. In this process, pressure is applied to force water through the membrane, leaving contaminants behind. It is widely used in desalination and water filtration systems to produce clean, drinkable water from seawater or contaminated sources.

[0006] Distillation is a process that separates liquids based on differences in their boiling points. Seawater is heated to produce steam, which rises and leaves the dissolved salts and14902-5654-6689.1Atty. Dkt. No. 046434-0971 impurities behind. The steam is then condensed back into liquid form, resulting in purified water.

[0007] Electrodialysis is a water treatment process that uses an electric field to move charged particles, such as salts, through selective ion-exchange membranes. These membranes allow cations to pass through one membrane and anions through another, effectively separating the salts from the water.

[0008] Capacitive deionization (CDI) is a water purification technology that removes dissolved ions by applying an electric field to electrodes, which attract and capture the ions. When water flows between the electrodes, positively charged ions are drawn to the negative electrode and negatively charged ions to the positive electrode. After the electrodes are saturated with ions, the system is “regenerated” by reversing the electric field, allowing the ions to be released and the electrodes to be ready for reuse.SUMMARY

[0009] A by-product of desalination processes, including RO, distillation, electrodialysis, and CDI, is brine. Brine is an aqueous solution with a concentration of sodium chloride higher than that of seawater, which is generally about 3.5 wt.%. Brine can also include valuable trace metals like silver, zinc, copper, and nickel. Brine is often discarded, and brine management remains an environmental challenge. The recovery of valuable trace metals may reduce the environmental impact of brine discharge, while creating a new resource stream. Chelating polymers such as polythiosemicarbazide (PTSC) may be used to recover these valuable trace metals. PTSC can form strong complexes with these trace metals ions.

[0010] In an aspect, a method of separating a metal ion from an aqueous solution is disclosed. The aqueous solution includes the metal ion. The method contacting the aqueous solution with a PTSC polymer of Formula I:where x is about 1 to about 250.24902-5654-6689.1Atty. Dkt. No. 046434-0971

[0011] The aqueous solution comprises about 0.5 wt.% to about 26 wt.% sodium chloride, and the metal ion comprises silver, copper, zinc, nickel, or a combination of any two or more thereof. Contacting the aqueous solution with the polymer of Formula I may include passing the aqueous solution through a packed bed column comprising the PTSC polymer.

[0012] In another aspect, a method of preparing a packed bed column for separating a metal ion from an aqueous solution is disclosed. The method includes packing the packed bed column with a polymer of Formula I.

[0013] In another aspect, a system is disclosed. The system includes a packed bed column comprising a polymer of Formula I or a porous membrane comprising the polymer of Formula I.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is an illustration of a system that includes a packed bed column comprising a polymer of Formula I.

[0015] FIG. 2 is a reaction scheme of the synthesis of the polymer of Formula I.

[0016] FIG. 3 is a reaction scheme of metal ion complexation with the polymer ofFormula I.

[0017] FIG. 4 is a graph of the adsorption profile of a mixture of metal ions (1 ppm each) by the system in FIG. 1.

[0018] FIG. 5 is a graph of the adsorption profiles for metal ions at concentrations of 0.1 ppm at pH 2 and 12 by the system in FIG. 1.

[0019] FIG. 6 is a graph of the desorption profiles of mixed metal ions from the system in FIG. 1 using thiourea at a flow rate of 5 mL / min. Adsorption conditions were 1 ppm metal ion at a flow rate of 5 mL / min and pH of 2.

[0020] FIG. 7 is a schematic illustration of an ultrafiltration setup for the pretreatment of seawater including a packed bed column comprising a polymer of Formula I.34902-5654-6689.1Atty. Dkt. No. 046434-0971

[0021] FIG. 8 is a graph of feed / retentate and permeate flow rate profiles during reverse osmosis (RO) operation for desalination of seawater. The inset is a picture of the RO membrane.

[0022] FIG. 9 is a graph of feed / retentate and permeate conductivity profiles during RO operation for desalination of seawater. The inset is a schematic of the RO filtration cell.

[0023] FIG. 10 is a graph of breakthrough curves for the adsorption to the packed bed column comprising the polymer of Formula I in FIG. 7 of hard metal ions (e.g., Ca2+, Na+, Mg2+, Cl") from the brine produced by RO operation.

[0024] FIG. 11 is a graph of the desorption profile for the adsorbed trace metals (e.g., Ni2+, Zn2+, Cu+, Cu2+, Ag+, Co2+, Mo2+, Mo6+, V3+, V5+) from the packed bed column comprising the polymer of Formula I in FIG. 7 after treatment of the RO brine in FIG. 7 with the packed bed column.

[0025] FIG. 12 is a graph of a zoomed in view of the graph in FIG. 11.DETAILED DESCRIPTION

[0026] Various embodiments are described hereinafter. It should be noted that the specific embodiments are not intended as an exhaustive description or as a limitation to the broader aspects discussed herein. One aspect described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced with any other embodiment(s).

[0027] As used herein, “about” will be understood by persons of ordinary skill in the art and will vary to some extent depending upon the context in which it is used. If there are uses of the term which are not clear to persons of ordinary skill in the art, given the context in which it is used, “about” will mean up to plus or minus 10% of the particular term.

[0028] The use of the terms “a” and “an” and “the” and similar referents in the context of describing the elements (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the44902-5654-6689.1Atty. Dkt. No. 046434-0971 specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the embodiments and does not pose a limitation on the scope of the claims unless otherwise stated. No language in the specification should be construed as indicating any non-claimed element as essential.

[0029] Disclosed herein are systems and methods of separating metal ions from aqueous solutions using a chelating polymer, and methods of preparing the chelating polymer for using in metal ion separation. For example, the aqueous solution may include a brine, seawater, brackish water, or a combination of any two or more thereof. As another example, the aqueous solution may be a produced oil water collected during crude oil production. The aqueous solution may include a higher concentration of dissolved sodium chloride and a lower concentration of trace metal ions (e.g., silver, copper, zinc, nickel). The chelating polymer may be in the form of a particulate suitable for packing into a packed bed column, a porous membrane, or another suitable form for adsorption of trace metals from the aqueous solution.

[0030] Also disclosed herein are systems and methods of separating metal ions from an aqueous solution using a packed bed column comprising the chelating polymer, and methods of preparing the packed bed column for separating metal ions from the aqueous solution. For example, the metal ions that may be separated may include silver, copper, zinc, nickel, or a combination of any two or more thereof. The aqueous solution may be a solution including a mixture of different dissolved ions or may be a solution including only the metal ion that is separated.

[0031] Also disclosed herein are systems and methods of separating metal ions from an aqueous solution using a porous membrane comprising the chelating polymer, and methods of preparing the porous membrane for separating metal ions from the aqueous solution. For example, the metal ions that may be separated may include silver, copper, zinc, nickel, or a combination of any two or more thereof. The aqueous solution may be a solution including a mixture of different dissolved ions or may be a solution including only the metal ion that is separated.

[0032] The chelating polymer may have the structure of Formula I:54902-5654-6689.1Atty. Dkt. No. 046434-0971where x is about 1 to about 250. The polymer of Formula I is also referred to herein as polythiosemicarbazide or PTSC. The chelating polymer may selectively separate silver, copper, zinc, nickel, or a combination of any two or more thereof from the aqueous solution including about 0.5 wt.% to about 26 wt.% sodium chloride .

[0033] In an aspect, a system includes a packed bed column comprising a polymer of Formula I. FIG. 1 is an illustration of a system 100 that includes a packed bed column 110 comprising a polymer 120. The polymer 120 may include the polymer of Formula I.

[0034] The polymer packed in the packed bed column 110 may have the form of particles. The particles may have an average diameter of about 1 pm to about 10,000 pm, e.g., about 10 pm to about 5000 pm, about 100 pm to about 4000 pm, about 200 pm to about 3000 pm, or about 400 pm to about 1500 pm.

[0035] The packed bed column 110 may include porous supports to contain the particulate polymer of Formula I. The supports may prevent compaction of the polymer and help maintain the height of the packed polymer in the column. For example, the porous supports may be disposed on opposite ends of the column with the particulate polymer of Formula I sandwiched therebetween. The porous supports may be made of a polymer, e.g., polytetrafluoroethylene (PTFE).

[0036] The packed bed column 110 may include a layer of beads disposed directly on the porous supports on the side of the porous support opposite the side directly disposed on the particulate polymer of Formula I. The beads may act as an inert packing material to provide even distribution of the flow across the polymer layer, thereby increasing the efficiency of the adsorption process. As a nonlimiting example, the inert beads may be zirconium.

[0037] In any embodiment, the system may include a porous membrane comprising the polymer of Formula I in place of or in addition to the packed bed column 110. Where the system includes the porous membrane in addition to the packed bed column 110, the porous membrane may be disposed upstream or downstream of the packed bed column 110, or may64902-5654-6689.1Atty. Dkt. No. 046434-0971 be incorporated into the packed bed column 110. The porous membrane may be a sheet, a hollow fiber, a fiber, a bead, or a particle. The system may include a housing to hold the porous membrane. The fibers or hollow fibers can be bundled longitudinally and arranged to extend along the direction of flow. The sheet can be spirally rolled, with the ends of the spiral facing the inlet and outlet openings of the membrane module.

[0038] The system 100 may include a vessel 130 to contain the aqueous solution including the metal ion. The vessel 130 may receive the aqueous solution as a brine from a desalination system. The vessel 130 may receive the aqueous solution as seawater from the sea. The vessel 130 may receive the aqueous solution as produced oil water from a crude oil extraction system.

[0039] The aqueous solution may include a mixture of metal ions and the packed bed column including the chelating polymer may selectively separate silver, copper, zinc, nickel, or a combination of any two or more thereof from the solution of mixed metal ions. For example, the packed bed column may separate trace metal ions (e.g., silver, copper, zinc, nickel) from aqueous solutions where the trace metal ions are at a concentration of less than 1 wt.% of the aqueous solution. For example, the packed bed column may separate silver ions from the aqueous solution.

[0040] The aqueous solution may include a mixture of metal ions. For example, the aqueous solution may be a brine, seawater, or brackish water. As another example, the aqueous solution may be a produced oil water collected during crude oil production. The aqueous solution may include a higher concentration of dissolved sodium chloride and a lower concentration of trace metal ions (e.g., silver, copper, zinc, nickel).

[0041] The aqueous solution may include a brine produced from a desalination process. Illustrative desalination processes include, but are not limited to, RO, distillation, electrodialysis, CDI, or a combination of any two or more thereof. As an example, the brine may include about 3 wt.% to about 7 wt.% sodium chloride, about 2 wt.% to about 5 wt.% magnesium chloride, about 1 wt.% to about 5 wt.% sulfates, about 0.5 wt.% to about 1.5 wt.% potassium chloride, about 0 wt.% to about 1 wt.% bromides, and less than 1 wt.% of trace metal ions (e.g., silver, copper, zinc, nickel).

[0042] The aqueous solution may include about 0.5 wt.% to about 26 wt.% sodium chloride, e.g., about 1 wt.% to about 20 wt.%, about 1 wt.% to about 15 wt.%, about 1 wt.%74902-5654-6689.1Atty. Dkt. No. 046434-0971 to about 12 wt.%, about 1 wt.% to about 10 wt.%, about 2 wt.% to about 8 wt.%, about 3 wt.% to about 7 wt.%, about 3 wt.% to about 4 wt.%, about 5 wt.% to about 7 wt.%, or about 3.5 wt.%.

[0043] The aqueous solution may include about 0 ppb to about 10 ppm silver ions, e.g., about 0.001 ppb to about 10 ppm, about 0.001 ppb to about 1 ppm, about 0.001 ppb to about 100 ppb, about 0.001 ppb to about 10 ppb, about 0.001 ppb to about 1 ppb, about 0.001 ppb to about 0.1 ppb, about 0.001 ppb to about 0.01 ppb. For example, the aqueous solution may include about 0.05 ppm to about 2 ppm silver ions, e.g., about 0.05 ppm to about 0.2 ppm, about 0.5 ppm to about 2 ppm, about 0.1 ppm, or about 1 ppm.

[0044] The aqueous solution may include about 0 ppb to about 10 ppm copper ions, e.g., about 0.001 ppb to about 10 ppm, about 0.001 ppb to about 1 ppm, about 0.001 ppb to about 100 ppb, about 0.001 ppb to about 10 ppb, about 0.001 ppb to about 1 ppb, about 0.001 ppb to about 0.1 ppb, about 0.001 ppb to about 0.01 ppb. For example, the aqueous solution may include about 0.05 ppm to about 2 ppm copper ions, e.g., about 0.05 ppm to about 0.2 ppm, about 0.5 ppm to about 2 ppm, about 0.1 ppm, or about 1 ppm.

[0045] The aqueous solution may include about 0 ppb to about 10 ppm nickel ions, e.g., about 0.001 ppb to about 10 ppm, about 0.001 ppb to about 1 ppm, about 0.001 ppb to about 100 ppb, about 0.001 ppb to about 10 ppb, about 0.001 ppb to about 1 ppb, about 0.001 ppb to about 0.1 ppb, about 0.001 ppb to about 0.01 ppb. For example, the aqueous solution may include about 0.05 ppm to about 2 ppm nickel ions, e.g., about 0.05 ppm to about 0.2 ppm, about 0.5 ppm to about 2 ppm, about 0.1 ppm, or about 1 ppm.

[0046] The aqueous solution may include about 0 ppb to about 10 ppm zinc ions, e.g., about 0.001 ppb to about 10 ppm, about 0.001 ppb to about 1 ppm, about 0.001 ppb to about 100 ppb, about 0.001 ppb to about 10 ppb, about 0.001 ppb to about 1 ppb, about 0.001 ppb to about 0.1 ppb, about 0.001 ppb to about 0.01 ppb. For example, the aqueous solution may include about 0.05 ppm to about 2 ppm zinc ions, e.g., about 0.05 ppm to about 0.2 ppm, about 0.5 ppm to about 2 ppm, about 0.1 ppm, or about 1 ppm.

[0047] The aqueous solution may have a pH of about 1 to about 13, and the pH of the aqueous solution may determine the metal ions separated by the packed bed column. For example, the aqueous solution may have a pH of about 1 to about 3, e.g., about 1.5 to about 2.5, or about 2, and the packed bed column may selectively separate silver ions, copper ions,84902-5654-6689.1Atty. Dkt. No. 046434-0971 or a combination thereof from the aqueous solution. As another example, the aqueous solution may have a pH of about 11 to about 13, e.g., about 11.5 to about 12.5, or about 12, and the packed bed column may selectively separate zinc ions, nickel ions, copper ions, or a combination of any two or more thereof. As another example, the aqueous solution may have a pH of about 1 to about 13, and the packed bed column may selectively separate copper ions.

[0048] The vessel 130 may be equipped with a pH meter to measure the pH of the aqueous solution. The vessel 130 may be configured to receive an acid and / or a base to adjust the pH of the aqueous solution. For example, the vessel 130 may include an inlet for the addition of acid and / or base.

[0049] The vessel 130 or a second vessel may be to contain the regeneration solution to regenerate the polymer of Formula I in the packed bed column. The regeneration solution may help desorb metal ions that are complexed to the polymer of Formula I.

[0050] The regeneration solution may include thiourea dissolved in a polar solvent (e.g., water, ethanol, methanol, or a combination of two or more thereof). The regeneration solution may have a concentration of thiourea of about 0.01 M to about 1.5 M, e.g., about 0.05 to about 1 M, about 0.05 M to about 0.5 M, about 0.05 M to about 0.2 M, or about 0.1 M. For example, the regeneration solution may have a concentration of 0.1 M thiourea.

[0051] The system 100 may include conduits 132 and 134. The conduits 132 and 134 may include channels, tubes, troughs, pipes, ducts, or similar for conveying the aqueous solution and / or the regeneration solution from the vessel 130 or another vessel to the packed bed column 110. During operation of the system 100, the packed bed column 110 may include the aqueous solution flowing past the polymer of Formula I.

[0052] The system 100 may include a pumping device 150 to pump the aqueous solution through the conduits 132 and 134 to the packed bed column 110. The pumping device 150 may be a pump. Illustrative pumps include, but are not limited to, hand pumps, peristaltic pumps, diaphragm pumps, piston pumps, gear pumps, and siphons. The pumping device 150 may provide pumping using the force of gravity. In some embodiments, the system 100 does not include the pumping device 150 and relies on other forces (e.g., gravity) to move the aqueous solution from the vessel 130 to the packed bed column 110.94902-5654-6689.1Atty. Dkt. No. 046434-0971

[0053] The pumping device 150 may be a pump configured to pump the aqueous solution and / or the regeneration solution at a flow rate. For a lab scale system, the flow rate may be about 1 mL / minute to about 10 mL / minute, e.g., about 2 mL / minute to about 8 mL / minute, about 4 mL / minute to about 7 mL / minute, or about 5 mL / minute. For example, the flow rate may be about 5 mL / minute. For larger scale systems (e.g., industrial scale), the flow rate may be about 1 mL / minute to about 10 L / minute, e.g., about 100 mL / minute to about 1000 mL / minute, about 1 L / minute to about 10 L / minute, or any value therebetween. The residence time may depend on the flow rate and the length of the column. For example, the residence time may be about 0.1 minute to about 10 minutes, e.g., about 0.1 minute to about 5 minutes, about 0.2 minutes to about 4 minutes, or about 0.2 minutes to about 3 minutes.

[0054] The system 100 may include vessel 140 to receive the modified aqueous solution following its passage through the packed bed column 110. The modified aqueous solution may include a different concentration of silver ions, copper ions, zinc ions, nickel ions, or a combination of any two or more thereof as compared to the concentration of the aqueous solution prior to introduction to the packed bed column. The modified aqueous solution may include a lower concentration of silver ions, copper ions, zinc ions, nickel ions, or a combination of any two or more thereof. For example, the modified aqueous solution may include about 1% to about 99.9% less of silver ions, copper ions, zinc ions, nickel ions, or a combination of any two or more thereof as compared to the initial concentration of the ions in the aqueous solution, e.g., about 1%, 5%, 10 %, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, 99%, or 99.9%. For example, the modified aqueous solution may include about 1% to about 99.9%, e.g., 99%, less silver ions. For example, the modified aqueous solution may include about 1% to about 99.9% less copper ions.

[0055] The vessel 140 or a fourth vessel may be to contain the modified regeneration solution after regenerating the polymer of Formula I in the packed bed column. The modified regeneration solution may include the desorbed metal ions that were complexed to the polymer of Formula I. The modified regeneration solution may include a higher concentration of silver ions, copper ions, zinc ions, nickel ions, or a combination of any two or more thereof as compared to the concentration of these metal ions in the regeneration solution prior to introduction to the packed bed column. For example, the modified regeneration solution may include about 1% to about 99.9% more of silver ions, copper ions, zinc ions, nickel ions, or a104902-5654-6689.1Atty. Dkt. No. 046434-0971 combination of any two or more thereof as compared to the initial concentration of the ions in the aqueous solution, e.g., about 1%, 5%, 10 %, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, 99%, or 99.9%. For example, the modified regeneration solution may include about 1% to about 99.9%, e.g., 99%, more silver ions. For example, the modified regeneration solution may include about 1% to about 99.9% more copper ions.

[0056] The system 100 may include a conduit 142 to convey the modified aqueous solution and / or the modified regeneration solution from the packed bed column 110 to the vessel 140. The conduit 142 may include channels, tubes, troughs, pipes, ducts, or similar structures for conveying the modified aqueous solution from the packed bed column 110 to the vessel 140.

[0057] In an aspect, a method of separating a metal ion from the aqueous solution including the metal ion is disclosed. The method includes passing the aqueous solution through a packed bed column comprising a polymer of Formula I. The metal ion may include silver, copper, zinc, nickel, or a combination of any two or more thereof.

[0058] Passing the aqueous solution through the packed bed column may include flowing the aqueous solution through the packed bed column at a flow rate of about 1 mL / minute to about 10 mL / minute, e.g., about 2 mL / minute to about 8 mL / minute, about 4 mL / minute to about 7 mL / minute, or about 5 mL / minute. For example, the flow rate may be about 5 mL / minute.

[0059] Passing the aqueous solution through the packed bed column may include removing about 1% to about 99.9% of silver ions, copper ions, zinc ions, nickel ions, or a combination of any two or more thereof as compared to the initial concentration of the ions in the aqueous solution, e.g., about 1%, 5%, 10 %, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, 99%, or 99.9%. For example, passing the aqueous solution through the packed bed may include removing about 1% to about 99.9%, e.g., 99%, of the silver ions. For example, the passing the aqueous solution through the packed bed may include removing about 1% to about 99.9% copper ions.

[0060] The method may further include adjusting the pH of the aqueous solution prior to passing the aqueous solution through the packed bed column. Adjusting the pH of the aqueous solution may include adding an acid and / or a base. For example, the acid and / or base may be114902-5654-6689.1Atty. Dkt. No. 046434-0971 added while measuring the pH of the solution to confirm the pH of the aqueous solution. The aqueous solution may be adjusted to a pH of about 1 to about 13, and the pH of the aqueous solution may determine the metal ions separated by the packed bed column. For example, the aqueous solution may be adjusted to have a pH of about 1 to about 3, e.g., about 1.5 to about 2.5, or about 2, and the packed bed column may selectively separate silver ions, copper ions, or a combination thereof from the aqueous solution. As another example, the aqueous solution may be adjusted to have a pH of about 11 to about 13, e.g., about 11.5 to about 12.5, or about 12, and the packed bed column may selectively separate zinc ions, nickel ions, copper ions, or a combination of any two or more thereof. As another example, the aqueous solution may be adjusted to have a pH of about 1 to about 13, and the packed bed column may selectively separate copper ions.

[0061] The method may further include regenerating the polymer of Formula I by desorbing metal ions complexed with the polymer. Regenerating the polymer may include passing a regeneration solution through the packed bed column to regenerate the polymer of Formula I. The regeneration solution may include thiourea dissolved in a polar solvent (e.g., water, ethanol, methanol, or a combination of two or more thereof). The regeneration solution may have a concentration of thiourea of about 0.01 M to about 1.5 M, e.g., about 0.05 to about 1 M, about 0.05 M to about 0.5 M, about 0.05 M to about 0.2 M, or about 0.1 M. For example, the regeneration solution may have a concentration of 0.1 M thiourea.

[0062] Regenerating the polymer may include passing a thiourea solution through the packed bed column at a flow rate of about 1 mL / minute to about 10 mL / minute, e.g., about 2 mL / minute to about 8 mL / minute, about 4 mL / minute to about 7 mL / minute, or about 5 mL / minute. For example, the flow rate may be about 5 mL / minute.

[0063] Regenerating the polymer may include desorbing about 1% to about 99.9% of silver ions, copper ions, zinc ions, nickel ions, or a combination of any two or more from the packed bed column, e.g., about 1%, 5%, 10 %, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, 99%, or 99.9%. For example, regenerating the polymer may include desorbing about 1% to about 99.9%, e.g., 99%, of the silver ions. For example, the regenerating the polymer may include desorbing about 1% to about 99.9% copper ions.124902-5654-6689.1Atty. Dkt. No. 046434-0971

[0064] In another aspect, a method of preparing the packed bed column for separating a metal ion from an aqueous solution is disclosed. The method of preparing the packed bed column may include packing the packed bed column with a polymer of Formula I.

[0065] The method of preparing the packed bed column may further include mechanically milling the polymer of Formula I to form a powder of the polymer of Formula I; and packing the packed bed column with the polymer of Formula I.

[0066] The method of preparing the packed bed column may further include forming the polymer of Formula I. FIG. 2 is a reaction scheme of the synthesis of the polymer of Formula I. The polymer of Formula I may be formed by reacting methylenebis(4- phenylisothiocyanate) (MPTC) and N,N-diaminopiperazine (DAP) in a solvent (e.g., dimethylsulfoxide (DMSO)) to form the polymer of Formula I.

[0067] Forming the polymer of Formula I may include separating the polymer of Formula I from the reaction mixture, including any reactants MPTC and DAP, and solvent. Separating may include phase separation of the polymer from the reaction mixture. Phase separation may include non-solvent induced phase separation, solvent-induced phase separation, thermal- induced phase separation, evaporation, supercritical fluid processing, lyophilization, or a combination of any two or more thereof.

[0068] Forming the polymer of Formula I may include drying the polymer of Formula I. Drying may include heating the polymer in an oven to evaporate solvent and moisture.

[0069] Forming the polymer of Formula I may include mechanically milling the polymer of Formula I to form particles of the polymer of Formula I appropriate for packing the packed bed column. Mechanically milling may include grinding the polymer into fine particles using, e.g., hand grinding, ball milling, cryogenic milling, high-speed rotary blade blending, or a combination of any two or more thereof.

[0070] Without being bound by any theory, FIG. 3 is a reaction scheme of metal ion complexation with the polymer of Formula I. The metal ion dissolved in the aqueous solution has a positive charge. The polymer of Formula I has a backbone with two complexing thiosemicarbazone (TSC) ligands per repeat unit that form complexes with the metal ion (e.g., silver ion, copper ion, nickel ion, zinc ion, or a combination of any two or more thereof). TSC is a good nucleophilic ligand owing to its 2 donor atoms in the molecule (S and N). It is134902-5654-6689.1Atty. Dkt. No. 046434-0971 considered a good chelation group since it has better coordination tendencies, forms more stable complexes, has better selectivity, and may form macrocyclic ligands. Based on the concept of hard-soft acid-base (HSAB) theory, this group belongs to soft base groups and can selectively trap noble metals that belong to soft acid groups.

[0071] The present invention, thus generally described, will be understood more readily by reference to the following examples, which are provided by way of illustration and are not intended to be limiting of the present invention.Examples.Example 1.

[0072] FIG. 4 is a graph of the adsorption profile of a mixture of metal ions (1 ppm each) by the system in FIG. 1.

[0073] The polymer of Formula I was prepared according to the reaction scheme of FIG. 2. The polymer of Formula I was synthesized through the polymerization of methylenebis(4- phenylisothiocyanate) (MPTC) and N,N-diaminopiperazine (DAP). The polymer was processed into a powder via non-solvent induced phase separation followed by drying in an oven. The dried polymer was mechanically ground into fine particles using a high-speed rotary blade blender. The grinding process was performed at room temperature under ambient conditions. The resulting particles were collected and sieved to obtain a uniform size distribution. The resulting particles were sieved using a grid so that the resulting particles had a diameter of about 400 pm to about 1500 pm.

[0074] The resulting polymer weight average molecular weight and the number average molecular weight were characterized using size exclusion chromatography. The polymer had a weight average molecular weight 53.3 kg / mol. The number average molecular weight of the polymer was 16.2 kg / mol. The polydispersity index (PDI) was 3.3.

[0075] The packed bed column was prepared with the polymer packed at a height of 1.5 cm and a diameter of 1.5 cm. The polymer volume was 2.65 cm3. The adsorption column was packed with the milled powder of the polymer of Formula 1, supported between layers of PTFE porous supports to maintain structural integrity and enable smooth filtration. Zirconium beads were disposed on the side of the PTFE supports opposite the side of the PTFE supports144902-5654-6689.1Atty. Dkt. No. 046434-0971 disposed on the polymer of Formula I. The PTFE acted as inert packing material, providing even distribution of the flow across the chelating polymer layer, increasing the efficiency of the adsorption process.

[0076] The adsorption column setup included a peristaltic pump, the packed bed column, and a feed tank. The feed solution was drawn from a reservoir and continuously pumped through the column using the peristaltic pump, which provided a controlled flow rate. As the feed passed through the column, the chelating polymer powder captured the selected metal ions via chelation, leaving the purified permeate to be collected at the bottom of the system. This setup provided continuous flow of the feed, providing efficient interaction between the solution and the adsorbent.

[0077] Experiments were conducted passing feed solution through the packed bed column using a peristatic pump. The feed / permeate metal ion solution concentrations were quantified using an Agilent 7800 inductively coupled plasma mass spectrometer (ICP-MS). The residence time was calculated from the flow rate of 2 mL / min or 5 mL / min and the column height of 1.5 cm. The residence time was 1.33 min for a flow rate of 2 mL / min, and 0.53 min for a flow rate of 5 mL / min. Unless otherwise specified, the packed bed column system of Example 1 was used in the following examples.

[0078] FIG. 4 describes adsorption behavior by polymer of Formula I of different metal ions as a mixture of ions in the aqueous solution under different pH conditions. The breakthrough curves are presented for a mixture of 1 L of aqueous solution in which multiple metal ions — nickel, copper, cobalt, vanadium, zinc, silver, and molybdenum — were dissolved at a concentration of 1 ppm each at a pH of 2 with a flow rate of 5 mL / min.

[0079] The graph in FIG. 4 indicated significant differences in adsorption behavior across the various metal ions. Except for silver and copper ions, the other metal ions showed no adsorption, with the concentration of the metal ions in the effluent remaining similar to that of the feed throughout the experiment. This data indicates a very weak affinity of the polymer of Formula I for metal ions nickel, cobalt, vanadium, zinc, and molybdenum at pH 2. The breakthrough curves approaching or exceeding C / Co = 0.8, indicated lower adsorption efficiency under these conditions. Copper showed considerable adsorption initially but started to saturate, as seen by the gradual increase in C / Co over time. The recovery of copper was estimated to be about 20% of the total weight of copper in the aqueous solution prior to154902-5654-6689.1Atty. Dkt. No. 046434-0971 contacting the polymer. Silver, as a soft acid, may favor forming complexation with the soft donor bases N and S atoms which are present in backbone of polymer of Formula I. Silver ions showed a higher amount of adsorption, with the concentration of silver in the effluent remaining near zero throughout the experiment, indicating a strong affinity of the polymer of Formula I for Ag+at pH 2. The recovery of silver was estimated to be 99% of the total weight of silver in the aqueous solution prior to contacting the polymer. The polymer of Formula I showed strong selective complexing towards some metal ions in the presence of a solution of mixed metal ions.Example 2.

[0080] Laboratory tests confirmed the efficacy of the polymer of Formula I in recovering trace metals from seawater and brine. The recovery percentages for copper, silver, zinc, and nickel were measured under different pH and flow rate conditions. The optimized process showed metal recovery efficiency of over 65% for some of the tested metals. The polymer of Formula I was stable over multiple regeneration cycles, maintaining its adsorption capacity after several uses.

[0081] FIG. 5 is a graph of the adsorption profiles for metal ions at concentrations of 0.1 ppm at pH 2 and 12 by the system in FIG. 1. FIG. 5 compares the adsorption of Mo, Cu, Zn, and V at two pH levels: pH 2 and pH 12 using 0.1 ppm concentration for each metal ion to determine the impact of pH on adsorption efficiency. Molybdenum and vanadium showed no interaction with the polymer of Formula I, as indicated by the lack of adsorption at both pH levels. Copper and zinc exhibited different adsorption behaviors depending on the pH level. Copper at pH 12 was only soluble when a low concentration was used (0.1 ppm). Results indicated that the adsorption behavior improved significantly for copper by changing the pH where adsorption went from 20% to 100% of the initial concentration of the copper ion. Similarly, zinc adsorption improved from 0% to 69% comparing pH 2 to pH 12. Copper and Zinc showed markedly improved adsorption at the higher pH. Without being bound by any theory, this may be due to enhanced deprotonation of the polymer’s functional groups, increasing their binding affinity for these metal ions. Results indicated that by altering pH, the polymer of formula I may selectively chelate with certain metal ions leading to impressive recovery percentages.164902-5654-6689.1Atty. Dkt. No. 046434-0971Example 3.

[0082] After metal adsorption, the polymer of Formula I was regenerated by passing a solution of 0.1 M thiourea through the packed bed column. Thiourea effectively desorbs the bound metal ions from the polymer, allowing the polymer to be reused for further adsorption cycles. This regeneration process was demonstrated to be efficient, recovering up to 98% of adsorbed metals.

[0083] FIG. 6 is a graph of the desorption profiles of mixed metal ions from the system in FIG. 1 using thiourea at a flow rate of 5 mL / min. Adsorption conditions were 1 ppm metal ion at a flow rate of 5 mL / min and pH of 2. FIG. 6 illustrates the desorption profiles of the same adsorption column in Figure 2 using a 0.1 M thiourea solution and a flow rate of 5 mL / min. Here, we observe that copper, which showed moderate adsorption (20%) in FIG. 4, was effectively desorbed, as indicated by the spike in copper concentration in thiourea followed by decreasing concentration over time. Calculating the amount of copper collected, revealed 0.2 mg, which indicated full desorption of copper. Additionally, silver, which had the highest adsorption, showed complete desorption, signifying a strong chelation to the polymer of Formula I and later strong desorption by thiourea. Analyzing the silver desorption profile revealed around 0.975 mg of silver in the regeneration solution after passing through the packed bed column, which indicated complete desorption. Other metals showed no desorption, which is consistent with their weak interaction with the polymer. The desorption curves indicate the effectiveness of thiourea in recovering certain metals like copper and silver from the polymer of Formula I.Example 4.

[0084] The metal recovery process with the packed bed column with the polymer of Formula I can be integrated with existing reverse osmosis (RO) systems. RO systems produce desalinated water and concentrate metals in the brine. By combining the polymer of Formula I adsorption process with RO, the present technology provides the recovery of valuable trace metals from the brine, reducing environmental impact and creating an additional resource stream. After RO filtration, the brine was directed through the packed bed column containing the polymer of Formula I for metal recovery.

[0085] FIG. 7 is a schematic illustration of an ultrafiltration setup for the pretreatment of seawater including a packed bed column comprising a polymer of Formula I using an ultrafine174902-5654-6689.1Atty. Dkt. No. 046434-0971 filtration process 710, followed by a reverse osmosis filtration process 720 and then absorption process 730. The series of experiments depicted in FIGS. 8-12 were conducted using the system in FIG. 7. The system in FIG. 7 was used to investigate the adsorption of trace metals from seawater brine, which has been concentrated through a sequence of ultrafiltration (UF) 710 and reverse osmosis (RO) processes 720. The system can exploit the higher concentration of trace metals in the brine to enhance adsorption efficiency using the polymer of Formula I.

[0086] The seawater used in the system in FIG. 7 was natural seawater collected from the Arabian Gulf near the shores of Yas Island, Abu Dhabi, UAE. The system in FIG. 7 included UF of the seawater to remove suspended solids, organic matter, and larger biological species. The UF step was used to provide efficient RO operation and prevent RO membrane fouling.

[0087] The RO system utilized a crossflow configuration, where the produced streams were split into permeate and concentrated retentate (brine). The RO membrane employed was a flat-sheet polyamide thin-film composite (PA-TFC) membrane, as shown in the inset of FIG. 8 fixed on the crossflow filtration cell (inset of FIG. 9).

[0088] FIG. 8 is a graph of feed / retentate and permeate flow rate profiles during reverse osmosis (RO) operation for desalination of seawater. The inset is a picture of the RO membrane. FIG. 9 is a graph of feed / retentate and permeate conductivity profiles during RO operation for desalination of seawater. The inset is a schematic of the RO filtration cell. The RO process was monitored through flow rate (FIG. 8) and conductivity (FIG. 9) measurements of the feed / retentate and permeate streams. The flow rates indicated stable operation with the permeate flow consistently lower than the feed / retentate flow, indicative of efficient concentration of the brine. The conductivity data indicated an increase in the conductivity of the feed / retentate over time, reflecting the accumulation of salts and trace metals in the brine. The permeate, with much lower conductivity, indicated effective rejection of ions by the RO membrane, indicating the brine was a concentrated source of trace metals for the subsequent packed bed column step.

[0089] Following RO filtration, the concentrated seawater brine was passed through a packed bed adsorption column containing the polymer of Formula I. FIG. 10 is a graph of breakthrough curves for the adsorption to the packed bed column comprising the polymer of Formula I in FIG. 7 of hard metal ions (e.g., Ca2+, Na+, Mg2+, Cl") from the brine produced184902-5654-6689.1Atty. Dkt. No. 046434-0971 by RO operation. The breakthrough curves in FIG. 7 indicated that more prevalent seawater ions (Ca, Na, Mg, Cl) were not significantly adsorbed by the polymer of Formula I, as evidenced by their high C / Co ratios near 1.0, similarly to observations with raw seawater experiments.

[0090] FIG. 11 is a graph of the desorption profile for the adsorbed trace metals (e.g., Ni2+, Zn2+, Cu+, Cu2+, Ag+, Co2+, Mo2+, Mo6+, V3+, V5+) from the packed bed column comprising the polymer of Formula I in FIG. 7 after treatment of the RO brine in FIG. 7 with the packed bed column. FIG. 12 is a graph of a zoomed in view of the graph in FIG. 11. The desorption data analyzed the trace metals (Ni, Zn, Cu, Ag, Co, Mo, V) recovered from the brine after adsorption. Notably, silver exhibited the higher desorption concentration, demonstrating the polymer’s strong affinity for silver even in the more concentrated brine environment. The collected silver amount registered at 0.0031 mg. The magnified view in FIG. 12 indicated that while more copper was adsorbed to the polymer of Formula I, other metals including zinc and nickel were also adsorbed. This suggested that the polymer of Formula I retained selectivity for silver, but with some potential for adsorbing other trace metals under the conditions tested. The results indicated the efficacy of using concentrated seawater brine, obtained via UF and RO, as a feed for metal recovery using the polymer of formula I.Example 5.

[0091] In this example, a chelating PTSC-based ultrafiltration membrane was evaluated for its ability to recover trace silver from real seawater. The seawater, collected from the Arabian Gulf coast of Abu Dhabi (UAE), was first subjected to a pretreatment step using a commercial polyethersulfone (PES) ultrafiltration membrane with a molecular-weight cutoff of 20 kDa. This pretreatment was carried out at 3 bar and a feed flow of 10 L h1and effectively removed suspended solids, natural organic matter, and other materials that could foul or obstruct the downstream chelating membrane. The extent of fouling on the PES membrane after operation was significant, as indicated by the accumulation of a noticeable brown deposit, indicating the usefulness of the pretreatment step for long-term stability.

[0092] After pretreatment, the seawater was processed using the PTSC chelating membrane operated at 2 bar and 35 L h '. This stage was configured to selectively bind trace metal ions through coordination with functional groups embedded within the PTSC polymer194902-5654-6689.1Atty. Dkt. No. 046434-0971 structure. During extended operation, an initial rapid decrease in permeate flux was observed, dropping from approximately 120 L m2h1to 18 L m2h1within the first day of filtration. Without being bound by any theory, this decline may be attributed to a combination of membrane compaction and progressive metal complexation within the hollow polymer matrix. Following this initial stabilization phase, the permeate flux remained consistently stable for more than 300 hours, indicating both mechanical robustness and sustained filtration performance.

[0093] The membrane did not hinder the passage of the dominant salt ions in seawater. Conductivity measurements of the feed, permeate, and retentate streams remained essentially identical throughout the entire process, indicating that major ions such as Na+, Cl", Mg2+, and Ca2+were transmitted freely through the membrane without rejection. This selectivity is consistent with the membrane’s design, which favors the complexation of specific trace metals while allowing the bulk ionic content of seawater to pass unchanged.

[0094] Evidence of metal uptake was visible through a clear color change in the PTSC membrane after seawater filtration, suggesting coordination of trace metals with the membrane’s functional groups. To quantify the adsorbed species, used membranes were thoroughly rinsed and digested using a microwave-assisted method involving concentrated nitric acid and hydrogen peroxide (8 mL HNCh + 1 mL H2O2, 200 °C, 40 min). This digestion mixture was intentionally free of chloride ions to avoid forming insoluble silver chloride during recovery.

[0095] Chemical analysis of the digested membranes revealed meaningful trends (Table 1). Under controlled conditions using a 10 ppm Ag+model solution, the PTSC membrane captured approximately 95 pg of silver, confirming its strong affinity for silver ions in the absence of competing species. However, when filtering 10 L of real seawater over a 14-day period, silver uptake decreased markedly to around 0.65 pg which was consistent with low concentration of silver in marine environments and the presence of Ag+as Ag-Cl species that are less accessible for binding. In contrast, other trace metals such as copper (about 5 pg) and iron (about 41.7 pg) were taken up in larger quantities, reflecting both their higher natural abundance in seawater and their favorable interaction with the nitrogen- and sulfur-containing donor atoms in the PTSC polymer. Lithium, being a hard monovalent cation, showed no measurable uptake, consistent with its lower affinity for soft chelating ligands.204902-5654-6689.1Atty. Dkt. No. 046434-0971Table 1 : Metal amounts recovered by PTSC membrane in different scenarios

[0096] While certain embodiments have been illustrated and described, it should be understood that changes and modifications can be made therein in accordance with ordinary skill in the art without departing from the technology in its broader aspects as defined in the following claims.

[0097] The embodiments, illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Thus, for example, the terms “comprising,” “including,” “containing,” etc. shall be read expansively and without limitation. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claimed technology. Additionally, the phrase “consisting essentially of’ will be understood to include those elements specifically recited and those additional elements that do not materially affect the basic and novel characteristics of the claimed technology. The phrase “consisting of’ excludes any element not specified.

[0098] The present disclosure is not to be limited in terms of the particular embodiments described in this application. Many modifications and variations can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods and compositions within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along214902-5654-6689.1Atty. Dkt. No. 046434-0971 with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods, reagents, compounds, compositions, or biological systems, which can of course vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0099] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0100] As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” “greater than,” “less than,” and the like, include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member.

[0101] All publications, patent applications, issued patents, and other documents referred to in this specification are herein incorporated by reference as if each individual publication, patent application, issued patent, or other document was specifically and individually indicated to be incorporated by reference in its entirety. Definitions that are contained in text incorporated by reference are excluded to the extent that they contradict definitions in this disclosure.

[0102] Other embodiments are set forth in the following claims.224902-5654-6689.1

Claims

Atty. Dkt. No. 046434-0971WHAT IS CLAIMED IS:

1. A method of separating a metal ion from an aqueous solution comprising the metal ion, the method comprising: contacting the aqueous solution with a polymer of Formula I:wherein x is about 1 to about 250; and wherein the aqueous solution comprises about 0.5 wt.% to about 26 wt.% sodium chloride; and the metal ion comprise silver ions, copper ions, zinc ions, nickel ions, or a combination of any two or more thereof.

2. The method of claim 1, wherein the aqueous solution is seawater, brine produced from desalination, or produced oil water.

3. The method of claim 1, wherein the aqueous solution has a pH of about 1 to about 3; and the metal ion comprises silver ions, copper ions, or a combination thereof.

4. The method of claim 1, wherein the aqueous solution has a pH of about 11 to about 13; and the metal ion comprises zinc ions, nickel ions, copper ions, or a combination of any two or more thereof.

5. The method of claim 1, wherein the metal ion comprises silver ions.

6. The method of claim 1, wherein contacting the aqueous solution comprises passing the aqueous solution through a packed bed column comprising the polymer of Formula I.

7. The method of claim 6, wherein passing the aqueous solution through the packed bed column comprises a residence time of about 0.2 minutes to about 3 minutes.234902-5654-6689.1Atty. Dkt. No. 046434-09718. The method of claim 6, further comprising preparing the packed bed column, the method of preparing the packed bed column comprising: mechanically milling the polymer of Formula I to form a powder of the polymer of Formula I; and packing the packed bed column with the polymer of Formula I.

9. The method of claim 6, further comprising passing a regeneration solution through the packed bed column to desorb the metal ion from the polymer of Formula I.

10. The method of claim 9, wherein the regeneration solution comprises about 0.05 M to about 2 M thiourea.

11. The method of claim 1, wherein contacting the aqueous solution comprises passing the aqueous solution through a membrane comprising the polymer of Formula I.

12. A method of preparing a packed bed column for separating a metal ion from an aqueous solution comprising: packing the packed bed column with a polymer of Formula Iwherein x is about 1 to about 250.

13. The method of claim 12, further comprising mechanically milling the polymer ofFormula I.

14. The method of claim 12, further comprising: reacting methylenebis(4-phenylisothiocyanate) (MPTC) and N,N-diaminopiperazine (DAP) in a solvent to form the polymer of Formula I; separating the polymer from the solvent via non-solvent induced phase separation; and drying the polymer of Formula I.244902-5654-6689.1Atty. Dkt. No. 046434-097115. A system comprising: a packed bed column comprising a polymer of Formula I:a porous membrane comprising the polymer of Formula I; wherein x is about 1 to about 250.

16. The system of claim 15, wherein the system comprises the packed bed column, the system further comprising: a first vessel to hold an aqueous solution comprising a first concentration of a metal ion, the metal ion comprising silver ions, copper ions, zinc ions, nickel ions, or a combination of any two or more thereof; a second vessel to collect a modified aqueous solution from the packed bed column; a first tube to convey the aqueous solution from the first vessel to the packed bed column; and a second tube to convey the modified aqueous solution from the packed bed column to the second vessel; wherein the modified aqueous solution comprises a second concentration of the metal ion.

17. The system of claim 16, further comprising a pumping device to pump the aqueous solution through the first tube.

18. The system of claim 15, wherein the system comprises the packed bed column, wherein the packed bed column further comprises the aqueous solution.

19. The system of claim 18, wherein the aqueous solution further comprises about 0.5 wt.% to about 26 wt.% sodium chloride.

20. The system of claim 18, wherein the aqueous solution is seawater, brine produced from desalination, or produced oil water.254902-5654-6689.1

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