Electrodes for selective removal of multivalent ions through capacitive deionization

1. A method of forming an electrode for capacitive deionization, comprising:

depositing a slurry onto a substrate, wherein the slurry comprises a porous material, a first crosslinkable hydrophilic polymer, and a crosslinker for the first crosslinkable hydrophilic polymer;

annealing the slurry deposited on the substrate to create a crosslinked porous layer on the substrate;

depositing a solution comprising an ion-exchange material, a second crosslinkable hydrophilic polymer, and a crosslinker for the second crosslinkable hydrophilic polymer onto the crosslinked porous layer;

chemically modifying the crosslinked porous layer with iminodiacetic acid; and

optionally annealing and/or drying the solution on the crosslinked porous layer,

wherein the slurry and/or the solution are aqueous.

2. The method of claim 1 , wherein depositing the slurry and/or solution is performed by one of spray coating, dip coating, spin coating, printing, slurry casting, or a flow-coating process.

3. The method of claim 1 , wherein the porous material is selected from the group consisting of carbonaceous materials, metal organic framework, hexacyanoferrates, carbonized biomaterials and mixtures thereof.

4. The method of claim 1 , wherein the first crosslinkable hydrophilic polymer is selected from the group consisting of polyvinyl alcohol, polyacrylic acid, polymethylmethacrylate, glycidylmethacrylate, partially sulfonated polystyrene polymers, polyamide, polyacrylamide, chitosan, or mixtures thereof.

5. The method of claim 4 , wherein the crosslinker for the first crosslinkable hydrophilic polymer is at least one of sulfosuccinic acid, formaldehyde, glyoxal, adipic aldehyde, a dicarboxylic acid, a tricarboxylic acid, a polycarboxlic acid, anhydrides, acid chlorides, and glutaraldehyde.

6. The method of claim 1 , wherein the ion-exchange material is an anion exchange polymer or a cation exchange polymer.

7. The method of claim 6 , wherein the ion-exchange material is dispersed in particulate form into the solution prior to deposition of the solution onto the crosslinked porous layer.

8. The method of claim 1 , wherein the second crosslinkable hydrophilic polymer is selected from the group consisting of polyvinyl alcohol, polyacrylic acid, polymethylmethacrylate, glycidylmethacrylate, partially sulfonated polystyrene polymers, polyamide, polyacrylamide, chitosan, or mixtures thereof.

9. The method of claim 8 , wherein the crosslinker for the second crosslinkable hydrophilic polymer is at least one of sulfosuccinic acid, formaldehyde, glyoxal, adipic aldehyde, a dicarboxylic acid, a tricarboxylic acid, a polycarboxlic acid, anhydrides, acid chlorides, and glutaraldehyde.

10. The method of claim 1 , wherein the slurry and the solution comprises no organic solvent.

11. A method of deionizing an aqueous fluid, comprising:

continuously flowing the aqueous fluid through a capacitive deionization reactor that includes at least one electrode fabricated according to claim 1 while applying a voltage between an anode and a cathode of the capacitive deionization reactor.

12. The method of claim 11 , further comprising:

regenerating the anode and the cathode by reversing the applied voltage.

13. A method of deionizing an aqueous fluid, comprising:

preparing at least one electrode by:

depositing a slurry onto a substrate, wherein the slurry comprises a porous material, a first crosslinkable hydrophilic polymer, and a crosslinker for the first crosslinkable hydrophilic polymer;

annealing the slurry deposited on the substrate to create a crosslinked porous layer on the substrate,

depositing a solution comprising an ion-exchange material, a second crosslinkable hydrophilic polymer, and a crosslinker for the second crosslinkable hydrophilic polymer onto the crosslinked porous layer;

chemically modifying the crosslinked porous layer with iminodiacetic acid; and

optionally annealing and/or drying the solution on the crosslinked porous layer,

wherein the slurry and/or the solution are aqueous; and

continuously flowing the aqueous fluid through a capacitive deionization reactor that includes the at least one electrode fabricated to selectively remove a targeted ion, while applying a voltage between an anode and a cathode of the capacitive deionization reactor.

14. The method of claim 13 , wherein the targeted ion selectively removed by the capacitive deionization reactor is at least one of monovalent cations, monovalent anions, multivalent cations and multivalent anions.

15. The method of claim 13 , wherein the capacitive deionization reactor is configured as a flow-by, flow-through, flow, faradaic, inverse, hybrid, or intercalating capacitive deionization reactor.

16. An apparatus for capacitive deionization reactions comprising:

a cathode;

an anode,

wherein at least one of the anode and/or cathode is a crosslinked porous electrode formed by the method of claim 1 ,

wherein the crosslinked porous electrode comprises substrate, a first porous layer deposited on the substrate, and a second layer deposited on the first porous layer;

wherein the first porous layer comprises a porous material and a crosslinked hydrophilic polymer, and the second layer comprises an ion exchange material, a crosslinked or non-crosslinked hydrophilic polymer, and optionally a crosslinker.

17. The apparatus of claim 16 , wherein the crosslinked ion-exchange layer is selective for at least one of monovalent cations, monovalent anions, multivalent cations and multivalent anions.