Impregnated electrode for capacitive deionisation, process for preparing it and apparatus employing the electrodes

Patent metadata

Field	Value
Publication number	US-2015307373-A1
Application number	US-201314650585-A
Country	US
Kind code	A1
Filing date	Nov 15, 2013
Priority date	Dec 11, 2012
Publication date	Oct 29, 2015
Grant date	—

Abstract

Disclosed is an electrode an electrode for capacitive deionization comprising • (i) an adsorbent having specific surface area of 100 m 2/g to 1300 m 2/g; • (ii) conductive carbon black; and • (iii) a binder; wherein said adsorbent is impregnated with a substance having conductivity in the range of 10 5 S/m to 10 7 S/m and standard hydrogen potential in the range of −0.3 V to −1.3 V. The electrode provides enhanced recovery and greater reduction in total solids and is more energy efficient. The process or preparing the electrode and a gravity fed water purification apparatus incorporating said electrode are also disclosed.

First claim

1 . An electrode for capacitive deionization comprising:
(i) an adsorbent having specific surface area of 100 m 2 /g to 1300 m 2 /g; (ii) conductive carbon black; and (iii) a binder;
wherein said adsorbent is impregnated with a substance having conductivity in the range of 10 5 S/m to 10 7 S/m and standard hydrogen potential in the range of −0.3 V to +1.3 V.

2 . An electrode as claimed in claim 1 wherein said adsorbent is selected from activated carbon, high specific surface area graphite (HSAG), carbon nanotubes (CNT), activated carbon, activated carbon fiber, a cation exchange resin, zeolite, smectite or vermiculite.

3 . An electrode as claimed in claim 2 wherein said adsorbent is activated carbon.

4 . An electrode as claimed in claim 2 or 3 wherein said substance is a noble metal.

5 . An electrode as claimed in claim 4 wherein said noble metal is silver.

6 . An electrode as claimed in claim 3 or 4 wherein percentage of silver impregnated on said activated carbon is 0.1% to 0.8% by weight of the adsorbent.

7 . An electrode as claimed in any one of the preceding claims 3 to 6 wherein ratio of activated carbon: binder: conductive carbon black is in the range of 5:2:3 to 8:1:0.5.

8 . An electrode as claimed in any one of the preceding claims wherein said binder is a thermoplastic binder.

9 . Use of an electrode as claimed in claim 1 for purification of water.

10 . A process for preparing an electrode for capacitive deionisation of water as claimed in claim 1 comprising the steps of:
(i) forming a mixture of 60 to 88 parts by weight of an adsorbent having specific surface area of 100 m 2 /g to 1300 m 2 /g, 5 to 30 parts by weight of thermoplastic polymeric binder and 2 to 20 parts by weight of conductive carbon black and including a fluid to said mixture wherein amount of said fluid is not more than four times the weight of said mixture;
(ii) casting the composition obtained in step (i) in a mold;
(iii) compressing said mold;
heating said mold to a temperature in the range 150 to 350° C.; and,

(iv) demoulding the moulded electrode,
wherein said adsorbent is impregnated with a substance having conductivity in the range of 10 5 S/m to 10 7 S/m and standard hydrogen potential in the range of −0.3 V to +1.3 V.

11 . A process as claimed in claim 11 wherein the fluid is water.

12 . A gravity-fed water purification device for removal of dissolved salts from water comprising a housing having a plurality of electrodes as claimed in claim 1 wherein said electrodes are connected to a source of DC power to provide voltage less than 1.4 V potential across the electrodes.

Assignees

• Conopco Inc Dba Unilever

Inventors

• Alencherry Tinto Johnichan
• Ghosh Somnath
• Rajanarayana Venkataraghavan

Classifications

• C02F2305/08

  Nanoparticles or nanotubes · CPC title

• C02F2103/10

  from quarries or from mining activities · CPC title

• C02F2101/10

  Inorganic compounds · CPC title

• C02F1/4691 Primary

  Capacitive deionisation · CPC title

• C02F1/4604

  for desalination of seawater or brackish water · CPC title