Electrochemical ion exchange with textured membranes and cartridge

• US 20070023290A1
• Filed: 07/26/2005
• Published: 02/01/2007
• Est. Priority Date: 07/26/2005
• Status: Active Grant

• Current Assignee: Zhejiang Langke Membrane Materials Technology Company Limited
• Original Assignee: Pionetics Corporation
• Inventors: Hawkins, John, Kayser, George, Nyberg, Eric, Schoenstein, Paul, Janah, Ashok, Holmes, James
• Granted Patent: US 7,780,833 B2
• Time in Patent Office: Days
• US Class Current: 204/520
• CPC Class Codes: B01D 2311/24 Quality control
• CPC Class Codes: B01D 2313/02 Specific tightening or locking mechanisms
• CPC Class Codes: B01D 2313/06 External membrane module supporting or fixing means
• CPC Class Codes: B01D 2313/44 Cartridge types
• CPC Class Codes: B01D 2321/223 Polarity reversal
• CPC Class Codes: B01D 2323/42 Details of membrane preparation apparatus
• CPC Class Codes: B01D 2325/06 Surface irregularities
• CPC Class Codes: B01D 61/445 with bipolar membranes; Water splitting
• CPC Class Codes: B01D 61/54 Controlling or regulating
• CPC Class Codes: B01D 63/10 Spiral-wound membrane modules
• CPC Class Codes: B01D 63/101 Spiral winding
• CPC Class Codes: B01D 63/103 Details relating to membrane envelopes
• CPC Class Codes: B01D 63/1031 Glue line or sealing patterns
• CPC Class Codes: B01D 69/02 characterised by their properties
• CPC Class Codes: C02F 1/469 by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
• CPC Class Codes: C02F 1/4693 electrodialysis
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

An electrochemical cell 102 comprises an ion exchange membrane 10 having anion and cation exchange materials. The membrane 10 can have separate anion and cation exchange layers 12, 14 that define a heterogeneous water-splitting interface therebetween. In one version, the membrane 10 has a textured surface having a pattern of texture features 26 comprising spaced apart peaks 28 and valleys 30. The membranes 10 can also have an integral spacer 80. A cartridge 100 can be fabricated with a plurality of the membranes 10 for insertion in a housing 129 of the electrochemical cell 102. The housing 129 can also have a detachable lid 96 that fits on the cartridge 100. The electrochemical cell 102 can be part of an ion controlling apparatus 120.

Claims

1. A cartridge for an ion exchanging electrochemical cell, the cartridge comprising:

(a) a plurality of textured membranes abutting one another, each membrane having;

(i) an anion exchange layer abutting a cation exchange layer to form a heterogeneous water-splitting interface therebetween; and

(ii) a textured surface having a pattern of texture features comprising spaced apart peaks and valleys.

2. A cartridge according to claim 1 wherein either:

(i) the peaks are ridges and the valleys comprise furrows between adjacent ridges, the ridges and furrows being generally parallel to a direction that solution travels across the membrane during use of the membrane;

or

(ii) the peaks comprise conical protrusions or mesas, and the peaks extend out from a substantially flat surface region which defines the valleys.

3. A cartridge according to claim 1 characterized in that the texture features comprise at least one of:

(i) a dimension is greater than the thickness of a stagnant layer formed at the membrane surface by a solution traveling across the membrane surface;

(ii) a dimension of at least about 2 microns;

(iii) a peak to peak distance d_pp of at least about 10 microns;

(iv) a peak to valley distance d_pv of at least about 10 microns;

(v) an aspect ratio d_pv/d_pp of at least about 0.1;

or

(vi) an aspect ratio d_pv/d_pp of more than about 0.1.

4. A cartridge according to claim 1 comprising an integral spacer on the textured membranes, the integral spacer characterized by at least one of:

(i) filaments on the textured surface.

(ii) a coating on the peaks of the texture features;

(iii) a thickness of less than about 1000 microns;

or

(iii) a thickness of less than about 500 microns.

5. A cartridge according to claim 1 wherein the textured membranes are spirally wound around a core tube, and are enclosed by end caps.

6. A cartridge according to claim 5 at least one end cap has a hole through which an electrode may pass.

7. A cartridge according to claim 5 wherein the spirally wound textured membranes are offset from one another.

8. A cartridge according to claim 7 wherein the textured membranes are offset from one another by a distance d_o=3.14*d_c/n, where d_c is the outer diameter of the core tube on which the membranes are wrapped.

9. A cartridge according to claim 7 wherein the top ends of the offset membranes area attached to one another.

10. A cartridge according to claim 11 wherein both end-caps have an O-ring seals.

11. An electrochemical cell for removing or exchanging ions from a solution stream, the electrochemical cell comprising a cartridge according to claim 1, and further comprising a housing comprising first and second electrodes about the cartridge.

13. A method of manufacturing a cartridge for an ion exchange electrochemical cell, the method comprising:

(a) forming a plurality of textured membranes, each membrane having (i) anion and cation ion exchange materials, and (ii) a textured surface having a pattern of texture features comprising peaks and valleys which are spaced apart from one another;

(b) forming an offset membrane stack of textured membranes which are offset from one another;

(c) providing a core tube and winding the offset membrane stack around the core tube to form a cartridge roll; and

(d) attaching top and bottom end caps to the cartridge roll.

12. An electrochemical ion exchange system comprising the electrochemical cell of claim 16 and further comprising:

(a) a power supply for supplying a voltage to the first and second electrodes; and

(b) a pump for flowing a solution stream through the electrochemical cell.

14. A method according to claim 13 comprising forming textured membranes with texture features having at least one of:

(i) a dimension greater than the thickness of a stagnant layer formed at the membrane surface by a solution traveling across the membrane surface;

(ii) a dimension of at least about 2 microns;

(iii) a peak to peak distance d_pp of at least about 10 microns;

(iv) a peak to valley distance d_pv of at least about 10 microns;

(v) an aspect ratio d_pv/d_pp of at least about 0.1;

or

(vi) an aspect ratio d_pv/d_pp of more than about 0.1.

15. A method according to claim 13 wherein (b) comprises laying the membranes on top of one another so that the top ends of the membranes are offset from one another in the same direction.

16. A method according to claim 15 comprises offsetting the top ends of the membranes by a distance d_o=3.14*d_c/n, where d_c is the outer diameter of the core tube on which the membranes are wrapped.

17. A method according to claim 15 comprising attaching the top ends of the offset membranes to one another by clips, glue, heat staking, rivets, sewing, staples, ultrasonic bonding or welding.

18. A method according to claim 13 wherein (c) comprises positioning the bottom surface of the offset membrane stack on the core tube and winding the stack around the core tube while maintaining a tension on the stack by pulling the membrane stack or applying a radial force.

19. A method according to claim 13 wherein (b) comprises forming one or more sub-assembly stacks of membranes.

20. A method according to claim 13 wherein (c) further comprises attaching an outer sleeve over the cartridge roll.

21. A method according to claim 20 comprising attaching the outer sleeve to the membranes prior to winding, and attaching the outer sleeve to itself with glue, a weld, or a fiber.

22. A method of forming an electrochemical cell, the method comprising providing a electrochemical cell housing having solution inlets and outlets, and positioning the cartridge roll formed according to claim 16 within the housing such that the core tube is fluidly connected to the solution outlet.

23. A method of manufacturing a cartridge for an ion exchange electrochemical cell, the method comprising:

(a) forming a plurality of textured membranes, each membrane having (i) anion and cation ion exchange materials, and (ii) a textured surface having a pattern of texture features comprising peaks and valleys which are spaced apart from one another;

(b) forming an offset membrane stack of the textured membranes by laying the membranes on top of one another so that the top ends of the membranes are offset from one another in the same direction, and attaching the top ends of the offset membranes to one another;

(c) providing a core tube and winding the offset membrane stack around the core tube to form a cartridge roll;

(d) wrapping an outer sleeve around the cartridge roll to overlap itself; and

(e) applying top and bottom end caps on the cartridge roll.

24. A method of forming an electrochemical cell, the method comprising:

(a) providing a housing of having solution inlets and outlets;

(b) forming a cartridge by;

(1) forming a membrane stack by laying membranes on top of one another so that the top ends of the membranes are offset from one another in the same direction, and attaching the top ends of the offset membranes to one another;

(2) providing a core tube and winding the offset membrane stack around the core tube to form a cartridge roll; and

(3) applying top and bottom ends on the ends of the cartridge roll; and

(c) positioning the cartridge roll within the housing of an electrochemical cell so that the core tube is fluidly connected to the outlet of the housing.

25. A housing for an electrochemical ion exchange cell comprising a cartridge having an end-cap extension with a flange, the housing comprising:

(a) a vessel having a sidewall connected to a bottom wall, a solution inlet, and a solution outlet; and

(b) a detachable lid that can be removably attached to the sidewall of the vessel, the detachable lid comprising a plate having a keyhole that extends therethorough, the keyhole comprising a first hole having a dimension larger than the end-cap extension, and a second hole which opens into the first hole, the second hole having a dimension smaller than the flange of the end-cap extension.

26. A housing according to claim 25 wherein the keyhole comprises a first hole that is circular and a second hole that is an elongated aperture with a semicircular end.

27. A housing according to claim 25 wherein the plate comprises a side surface having a thread for screwing into a receiving thread in the sidewall of the vessel.

28. A housing according to claim 25 wherein the plate comprises a handle which assists an operator in screwing the lid.

29. An electrochemical cell comprising the housing of claim 25, and further comprising a cartridge having a plurality of spiral wrapped membranes, the membranes having a textured surface, and electrodes about the membranes.

30. A housing for an electrochemical ion exchange cell comprising a cartridge having a core tube, the housing comprising:

(a) a vessel having a sidewall connected to a bottom wall, a solution inlet, and a solution outlet; and

(b) a detachable lid that can be removably attached to the sidewall of the vessel, the detachable lid comprising a plate with a hollow post extending outwardly therefrom, the hollow post sized to slide into or over the end-cap extension of the cartridge of the electrochemical cell.

31. A housing according to claim 30 further comprising a groove about the base of the hollow post and an O-ring in the groove.

32. A housing according to claim 30 wherein the plate comprises a side surface having a plurality of pins extending outwardly therefrom, the pins sized to fit into a recessed groove in the sidewall of the vessel.