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US-12624415-B2 - Functionalized adsorbents for the recovery of rare earth elements from aqueous media

US12624415B2US 12624415 B2US12624415 B2US 12624415B2US-12624415-B2

Abstract

The disclosure relates to the design and synthesis of selected ligands, dendrimers, polymers and other solid phase substrates for selective chelation of rare earth elements (i.e. lanthanides), and use of those selective ligands for synthesis of resins, polymers and other types of solid supports for separation and recovery of lanthanides from aqueous media. Recovery of critical elements from aqueous media occurs in a simple two-step process: pre-concentration of REE on the adsorbent and recovery by acid elution. The present invention can be used for design of selective ligands immobilized on solid substrates for extraction of various constituents, such as lanthanides, actinides, radionuclides, trace metals, etc., from aqueous media.

Inventors

  • Athanasios Karamalidis
  • Newell R. Washburn
  • Clinton W. Noack
  • Kedar Perkins
  • David A. Dzombak

Assignees

  • CARNEGIE MELLON UNIVERSITY, A PENNSYLVANIA NON-PROFIT CORPORATION

Dates

Publication Date
20260512
Application Date
20161013

Claims (13)

  1. 1 . A method of recovering a rare earth element from aqueous media, comprising: providing an adsorbent, wherein the adsorbent comprises: a substrate comprising sulfonated polystyrene having an amine derived from diamine functionalization of imidoacetate moieties, wherein the substrate is acid and base resistant, and a material having at least one carboxyl group and a plurality of anhydride groups attached to a surface of the substrate through an amide bond between the carboxyl group on the material and the amine on the substrate, wherein the plurality of anhydride groups hydrolyze to form additional carboxyl groups in an aqueous environment, wherein the material selectively binds with at least one rare earth element in an aqueous solution via at least one additional carboxyl group on the surface-bound material; exposing the adsorbent to the aqueous media, wherein the rare earth element binds to the material on the surface of the substrate; rinsing the adsorbent in an acid; and recovering the rare earth element from the acid.
  2. 2 . The method of claim 1 , further comprising: exposing the adsorbent to the aqueous media after rinsing the adsorbent in the acid; rinsing the adsorbent again in a second acid; and recovering the rare earth element from the second acid.
  3. 3 . The method of claim 1 , wherein the material is a ligand.
  4. 4 . The method of claim 3 , wherein the ligand comprises diethylenetriaminepentaacetic dianhydride.
  5. 5 . The method of claim 3 , wherein providing an adsorbent comprises: adding diethylenetriaminepentaacetic dianhydride and N,N′-dicyclohexylcarbodiimide to a container; adding dichloromethane and (3-Aminopropyl)triethoxysilane to the container; filtering contents of the container to obtain the ligand; adding the ligand, dry toluene, and the substrate to a second container; and washing the substrate containing the ligand with toluene, then tetrahydrofuran, and then water.
  6. 6 . An adsorbent comprising: a substrate comprising sulfonated polystyrene having an amine derived from diamine functionalization of imidoacetate moieties, wherein the substrate is acid and base resistant; and a material having at least one carboxyl group and a plurality of anhydride groups attached to a surface of the substrate through an amide bond between the carboxyl group on the material and the amine on the substrate, wherein the anhydride groups hydrolyze to form additional carboxyl groups in an aqueous environment, wherein the material selectively binds with at least one rare earth element in an aqueous solution via at least one additional carboxyl group on the surface-bound material.
  7. 7 . The adsorbent of claim 6 , wherein the material is a ligand.
  8. 8 . The adsorbent of claim 7 , wherein the ligand comprises diethylenetriaminepentaacetic dianhydride.
  9. 9 . The adsorbent of claim 7 , wherein the ligand is created by: adding diethylenetriaminepentaacetic dianhydride and N,N′-dicyclohexylcarbodiimide to a container; adding dichloromethane and (3-Aminopropyl)triethoxysilane to the container; and filtering contents of the container to obtain the ligand.
  10. 10 . The adsorbent of claim 6 , wherein the material is diethylenetriaminepentaacetic dianhydride and the carboxyl group emanates from a central, tertiary amine of the diethylenetriaminepentaacetic dianhydride.
  11. 11 . The adsorbent of claim 6 , wherein the adsorbent is reusable after acid elution.
  12. 12 . An adsorbent for use in an aqueous environment comprising: a substrate consisting of polystyrene functionalized with an amine, and a material attached to a surface of the substrate through an amide bond between a single carboxyl group on the material and a single amine on the surface of the substrate, wherein the material comprises a plurality of anhydride functional groups, wherein the material selectively binds with at least one rare earth element via at least one additional carboxyl group formed on the surface-bound material from the anhydride functional groups in the aqueous environment.
  13. 13 . The adsorbent of claim 12 , wherein the material is diethylenetriaminepentaacetic dianhydride and the single carboxyl group emanates from a central, tertiary amine of the diethylenetriaminepentaacetic dianhydride.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. § 119 of Provisional Application Ser. No. 62/284,916, filed Oct. 13, 2015, Provisional Application Ser. No. 62/386,712, filed Dec. 10, 2015, and Provisional Application Ser. No. 62/494,656, filed Aug. 16, 2016, each of which is incorporated herein by reference. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH This invention was made with government support under Grant No. DE-EE0006749 awarded by the Department of Energy. The government has certain rights in the invention. BACKGROUND OF THE INVENTION This invention relates generally to the recovery of rare earth elements from aqueous media. More specifically, this invention relates to the design and synthesis of solid phase substrates that can be used to recover specific rare earth elements from aqueous media containing various components. Rare Earth Elements (REE) constitute a group of chemically similar metals in the lanthanide series plus Yttrium and Scandium. REE are a critical part of modern energy technologies and electronics. However, REE are highly dispersed in the earth's crust, making it costly and difficult to extract and concentrate them for industrial use. The high demand of the use of REE in advanced energy technologies makes urgent the need for alternative approaches for REE separation and recovery from different matrices compared to traditional mining and extraction operations. Aqueous media such as natural waters, sea water, brines, and waste waters produced from conventional oil/gas and shale gas extraction or thermal energy operations, offer a new opportunity for recovery of REE. Separation techniques for lanthanides and actinides from water have been employed in various industries, such as nuclear power generation. However, most of those strategies target the separation of actinides from lanthanides but they do not address the challenges of separating individual lanthanide elements and do not attempt to separate REE present at low concentration in hypersaline water, such as brines. In other words, recovering REEs from complex aqueous media is challenging because existing separation technologies for REE are not adequately selective or involve many chemical steps which increase the overall cost of the process. Ionic Imprinted Polymer (IIP) is an effective way to separate one REE element from other REE, such as selectively absorbing Gd from La. IIP utilizes metal ions as a template and imprinting the size and/or shape of the ions into the polymer by the process of polymerization. A properly formed polymer will selectively form bonds with the target ions rather than interfering ions due, thus separating target ions from other ions with similar properties. However, the various methods of IIP synthesis suffer from drawbacks, especially when used in complex or low-concentration solutions. For example, using a chemical immobilization method of synthesis, the loading rate is around 10% or less because the ligand can be blocked by the bulk structure of the polymer and the template ion cannot be leached out during the acid washing, making the ligand unavailable for ions in solution. Although IIPs can be developed for most REE, the effectiveness can vary across depending on the element being targeted. For example, Er-IIP has a mediocre selectivity and the separation factor is around 5 for Y, Dy, Ho, Tb, Tm. In addition, the IIPs for Gd, Tm, and Y have the highest selectivity not to the template element, but another one. For example, Gd-IIP has the highest selectivity to Eu instead of Gd. In addition, many IIPs are designed to attract medium or heavy REEs, except Nd-IIP. It is a challenge to develop an IIP for light elements such as La. Ligands have also been used to bind REE. Use of ligands has typically focused on simple systems containing low concentrations of background electrolytes and high sorbate concentrations. However, extraction from complex solutions, such as brines, that contain low levels of REE requires selective, high-capacity adsorbents in order to be effective and economical. Rare earth elements are abundant in Earth's crust but are highly dispersed. Currently the global production of rare earth elements is based on mining ore deposits and processing and refining of the mining extracts. However, different types of water (for example, seawater, groundwater, tailings, etc.) contain levels of rare earth elements. Traditional mining techniques would be unable to recover these elements. It would therefore be advantageous to develop materials that can concentrate and extract REE from aqueous media. BRIEF SUMMARY According to one embodiment of the present invention is a functionalized adsorbent used for extracting rare earth elements from aqueous solutions. The adsorbent comprises a solid substrate with a rare earth element (REE)-attractive material disposed on the surface of the substrate. Solid-phase extraction (SPE) of REEs from aqueous matrices ha