WO1994026669B1

WO1994026669B1 - A planar, flow-through, electric, double-layer capacitor and method of treating fluids with the capacitor

Info

Publication number: WO1994026669B1
Application number: PCT/US1994/005364
Authority: WO
Filing date: 1994-05-12
Publication date: 1995-01-12
Anticipated expiration: 1995-11-17

Abstract

The object of the invention is to provide a flow-through, electric, double-layer capacitor providing for a high, steady rate of removal of ionic substances and amenable to commercial scale application and a method of treating fluids using the flow-through electric double-layer capacitor. The invention is a planar, flow-through, electric, double-layer capacitor comprising a separator (1) consisting in an electrically-insulating, porous, flow-through sheet, activated carbon layers (2, 2), each comprising a high specific surface area activated carbon as a main component, collectors (3, 3) disposed externally of the active carbon layers (2, 2), and retaining plates (4, 4) disposed externally of the collectors (3, 3). A fluid containing ionic substances is treated by passing the fluid through the planar, flow-through, electric, double-layer capacitor and repeating, in alternate cycles, application of a direct current constant voltage to collectors (3, 3) and short-circuiting or reversal of connection between collectors (3, 3).

Claims

AMENDED CLAIMS

[received by the International Bureau on 14 November 1994 (14.11.94); original claims 1-3 cancelled; new claims 4-17 added (3 pages)]

Claim 4. A planar, flow through, electric, double layer capacitor for the treating of an ionic-containing fluid, which capacitor comprises: a) an electrically-insulating, porous, flow-through separator sheet (1); b) activated carbon layers (2)(2), each comprising a high specific surface area of activated carbon and disposed externally on either side of the separator sheet; c) electrode collector layers (3)(3), each comprising electrically conductive material and disposed externally on either side of the activated carbon layers and in intimate electrical contact with each activated carbon layer to form an anode and cathode electrode; d) retaining plates (4) (4) disposed externally of said electrical collectors to retain in uniform compaction the separator, activated carbon layers and collector layers together; e) inlet means (6) to permit the introduction of a fluid to be treated; f) outlet means (7) to permit the withdrawal of the treated fluid.

Claim 5. The capacitor of claim 4 which includes frame-shaped gaskets (5)(5) comprising electrically insulating material, said gaskets interposed between the said collectors (3)(3) and the retaining plates (4) (4).

Claim 6. The capacitor of claim 4 wherein the separator comprises a paper, a polymer, a fiber or a cloth material.

Claim 7. The capacitor of claim 4 wherein the activated carbon layers (2)(2) have a BET of not less than lOOOmVg-

Claim 8. The capacitor of claim 4 wherein the activated carbon layers (2)(2) comprise a porous sheet formed from a heat-treated mixture of powdery or granular activated carbon, a binder and a dispersing medium.

Claim 9. The capacitor of claim 8 wherein the said porous, formed sheet comprises activated carbon having a BET of not less than 1500m/9 and polytetrafluoroethylene, phenolic resin or carbon black or combinations thereof as a binder.

Claim 10. The capacitor of claim 4 wherein the electrical collectors have a portion thereof with flow- through orifices (3a).

Claim 11. The capacitor of claim 4 wherein the electrical collectors have outwardly extending, integral terminals (30) for connection to an electrical power source.

Claim 12. The capacitor of claim 4 wherein the electrical connectors (3)(3) comprise copper plates, aluminum plates, carbon-based or graphite foils.

13 Claim 13. The capacitor of claim 4 wherein the thickness of the activated carbon layers ranges from about 0.1mm to 3mm and the thickness of the electrical connector ranges from about 0.1mm to 0.5mm.

Claim 14. The capacitor of claim 4 which includes a direct current, constant voltage electrical power source connected to the electrical connectors to form an anode and a cathode, the power source having a voltage of about 0.5 to

5 volts.

Claim 15. The capacitor of claim 14 which includes means for the periodic short circuiting or reversal of the electrical connection to permit the desorbing and discharging of absorbed ions.

Claim 16. A method of treating a fluid containing an ionic substance which comprises: a) introducing the fluid into the inlet means of the capacitor of claim 1 while applying a direct current, constant voltage to said collectors (3)(3) to absorb ionic substances on the activated carbon layers; b) withdrawing a treated fluid from the outlet means; c) short circuiting or reversing periodically the electrical connectors (3)(3) of said capacitor to desorb ionic substances; and d) withdrawing said desorbed ionic substances from the outlet means.

Claim 17. The method of claim 15 wherein the fluid comprises an aqueous sodium chloride solution.

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