Ion concentration polarization-electrocoagulation hybrid water treatment system

• US 9,850,146 B2
• Filed: 09/17/2015
• Issued: 12/26/2017
• 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
• Primary Examiner(s): Phasge, Arun S
• Application Number:
  US14/857,133
• Publication Number:
  US 20170066665A1
• Time in Patent Office: 831 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 an electric field 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;

c. electrocoagulating particles within the water stream; and

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

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.

12. The method of claim 10, wherein a voltage or current in the overlimiting regime is applied.

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, wherein the electrocoagulation step is conducted simultaneously with the desalination step.

16. The method of claim 1, wherein the solution undergoes the electrocoagulation step first, followed by the desalination step, or vice versa.

17. The method of claim 1, wherein the electric field is created with a metal anode.

18. The method of claim 17, wherein the nonionic porous membrane is located at the desalted outlet of the at least a first channel.

19. The method of claim 17, wherein the metal anode is sacrificial.

20. The method of claim 1, wherein the ion exchange membranes are any combination of anion and cation exchange membranes.

21. The method of claim 1, wherein the metal anode comprises aluminum or iron.

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

23. The method of claim 1, wherein the electric field creates a boundary layer comprising at least one electroconvective vortex proximal to the at least one ion exchange membrane.

24. The method of claim 1, wherein the electric field is created by an electrode and a ground each located external and parallel to the channel.

25. The method of claim 1, wherein a second channel is formed between the at least one ground and the at least one ion exchange membrane.

26. The method of claim 25, wherein the second channel is filled with an electrolyte solution.

27. The method of claim 1, wherein the electrolyte solution is the first water stream.

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

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

30. The method of claim 1, further comprising at least one sedimentation tank, the at least one sedimentation tank comprising:

at least one sample inlet;

at least one sample outlet; and

at least one coagulate outlet; and

wherein the at least one sample outlet provides the at least first water stream.

31. A method of purifying and/or concentrating a first water stream containing ionic impurities and/or nonionic impurities through hybridized electrocoagulation and ion concentration polarization, the method comprising:

a. directing the first water stream into at least a first channel, the at least a first channel comprising;

at least one metal anode, at least one ground, at least one ion exchange membrane, at least one sample inlet, at least one anode outlet, at least one desalted outlet, and at least one concentrate outlet; and

b. applying an electric field across the first water stream;

whereby electrocoagulation occurs near the at least one metal anode;

ions pass through the ion exchange membrane forming an ion depletion zone, the ion depletion zone comprising a purified water stream;

an ion enrichment zone is formed, the ion enrichment zone comprising a concentrated ion aqueous stream; and

c. collecting the coagulant-rich stream at the at least one anode outlet and removing coagulated impurities by settling/floating to obtain purified water, and/or collecting the purified water stream at the at least one desalted outlet, and/or collecting the concentrated ion aqueous stream at the concentrate outlet;

d. sharing the electrodes between electrocoagulation and ion concentration polarization desalination systems to perform both processes within a single electrochemical system, in order to reduce unnecessary voltage drop near the electrodes.