Ion Concentration Polarization-Electrocoagulation Hybrid Water Treatment System

• US 20180141832A1
• Filed: 11/17/2017
• Published: 05/24/2018
• Est. Priority Date: 06/19/2013
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Choi, Siwon, Han, Jongyoon
• Granted Patent: US 10,099,945 B2
• Time in Patent Office: Days
• CPC Class Codes: B01D 2311/2642 Aggregation, sedimentation, flocculation, precipitation or coagulation
• CPC Class Codes: B01D 61/42 Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
• CPC Class Codes: B01D 61/46 Apparatus therefor
• CPC Class Codes: B01D 61/462 comprising the membrane sequence AA, where A is an anion exchange membrane
• CPC Class Codes: B01D 61/464 comprising the membrane sequence CC
• CPC Class Codes: C02F 1/4604 for desalination of seawater or brackish water
• CPC Class Codes: C02F 1/463 by electrocoagulation
• CPC Class Codes: C02F 1/469 by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
• CPC Class Codes: C02F 2103/08 Seawater, e.g. for desalination
• CPC Class Codes: C02F 2201/46115 Electrolytic cell with membranes or diaphragms

Abstract

Between two juxtaposed similar ion exchange membranes (AEMs or CEMs), an ion depletion zone and ion enrichment zone are generated under an electric field. As cations are selectively transferred through the CEMs, for example, anions are relocated in order to achieve electro-neutrality, resulting in the concentration drop (increase) in ion depletion (enrichment) zone. The use of a sacrificial metal anode allows electrocoagulation (EC) concurrently with ICP thereby permitting concentration of both ionic and non-ionic impurities to occur at the same time within the same cell or device.

Claims

1. A method of purifying and/or concentrating a first water stream containing ionic impurities comprising:

a. directing the water stream in a channel comprising an inlet and an outlet and defined, at least in part by two juxtaposed ion exchange membranes, wherein the ion exchange membranes are characterized by the same charge,

b. applying a voltage or current in the overlimiting regime across the water stream channel;

whereby, an ion depletion zone (d_de) comprising a purified water stream and an ion enrichment zone (d_en) comprising a concentrated ion aqueous stream are generated and ions are transferred through the ion exchange membranes;

collecting the purified water stream and/or the concentrated ion aqueous stream.

2. The method of claim 1, wherein the channel formed by the two juxtaposed ion exchange membranes does not contain a membrane carrying a charge counter to the two juxtaposed ion exchange membranes.

3. The method of claim 1, wherein the two juxtaposed ion exchange membranes are cationic exchange membranes.

4. The method of claim 1, wherein the two juxtaposed ion exchange membranes are anionic exchange membranes.

5. The method of claim 1, further comprising a nonionic porous membrane separating or bifurcating the ion depletion zone and the ion enrichment zone.

6. The method of claim 5, wherein the nonionic porous membrane is located at the outlet of the channel.

7. The method of claim 1 wherein the electric field creates a boundary layer comprising at least one electroconvective vortex proximal to at least one of the two juxtaposed ion exchange membranes.

8. The method of claim 7, wherein the electric field is created by an electrode and a ground each located external and parallel to the channel.

9. The method of claim 8, wherein the electrode forms a second channel with the first of said two juxtaposed ion exchange membranes and the ground forms a third channel with the second of said two juxtaposed ion exchange membranes.

10. The method of claim 9, wherein the second and third channel are filled with an electrolyte solution.

11. The method of claim 10, wherein the electrolyte solution is the first water stream.

13. The method of claim 1 wherein the first water stream comprises salt.

14. The method of claim 1 wherein the first water stream comprises biomolecules.

15. The method of claim 1 further comprising the step of electrocoagulation.

16. The method of claim 15, wherein the electrocoagulation step is conducted simultaneously with the desalination step.

17. The method of claim 15, wherein the solution undergoes the electrocoagulation step first, followed by the desalination step, or vice versa.

18. The method of claim 15, wherein the electric field is created with a metal anode.

33. The method of claim 1, wherein the ion exchange membranes are microporous.

34. The method of claim 1, wherein the ion exchange membrane is nanoporous.

12. (canceled)

19. The method of claim 19, wherein the metal anode is sacrificial.

20-32. -32. (canceled)