Functionalized adsorbents for the recovery of rare earth elements from aqueous media
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.
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 . 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 . The method of claim 1 , wherein the material is a ligand.
4 . The method of claim 3 , wherein the ligand comprises diethylenetriaminepentaacetic dianhydride.
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 . 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 . The adsorbent of claim 6 , wherein the material is a ligand.
8 . The adsorbent of claim 7 , wherein the ligand comprises diethylenetriaminepentaacetic dianhydride.
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 . 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 . The adsorbent of claim 6 , wherein the adsorbent is reusable after acid elution.
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 . 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.