Electrodialysis apparatus and process

• US 4,608,140 A
• Filed: 06/10/1985
• Issued: 08/26/1986
• Est. Priority Date: 06/10/1985
• Status: Expired due to Fees

• Current Assignee: Ionics Incorporated
• Original Assignee: Ionics Incorporated
• Inventors: Goldstein, Arthur L.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Chapman, Terryence
• Application Number:
  US06/743,219
• Time in Patent Office: 442 Days
• Field of Search: 204/182.4, 204/182.6, 204/301, 204/182.3
• US Class Current: 435/173.9
• CPC Class Codes: A23C 9/144 by electrical means, e.g. electrodialysis
• CPC Class Codes: B01D 2313/14 Specific spacers
• CPC Class Codes: B01D 2321/223 Polarity reversal
• CPC Class Codes: B01D 61/44 Ion-selective electrodialysis
• CPC Class Codes: B01D 61/46 Apparatus therefor
• CPC Class Codes: B01D 61/461 comprising only a single cell, only one anion or cation exchange membrane or one pair of anion and cation membranes

Abstract

Apparatuses and processes are described for transferring electrolytes from one electrolytically conducting solution to another, said apparatus comprising a pair of spaced electrodes; at least one pair of spaced electrolytically conducting barriers between said electrodes, one of said barriers having a transport number for ions of one sign substantially greater than that of said solutions and of the other barrier, means for applying a substantially direct current electrical potential between said electrodes in a direction to cause electrolyte to the transferred out of the space between said barriers; a plurality of fluid permeable tubules between said barriers; means for introducing fluid into at least one end of such tubules; and means for withdrawing fluid from the space between said barriers.

Claims

1. Apparatus for transferring electrolytes from one electrolytically conducting solution to another, said apparatus comprising:

(a) a pair of spaced electrodes;

(b) at least one pair of spaced electrolytically conducting barriers between said electrodes, one of said barriers having a transport number of ions of one sign substantially greater than that of said solutions and of the other barrier;

(c) a plurality of fluid permeable tubules between said barriers;

(d) means for introducing fluid into at least one end of such tubules;

(e) means for applying a substantially direct current electrical potential between said electrodes in a direction to cause electrolyte to be transferred out of the space between said barriers; and

(f) means for withdrawing fluid from the space between said barriers.

2. Apparatus according to claim 1 in which said one of said barriers is a cation selective membrane and said other barrier is selected from the group consisting of anion-selective membranes and substantially non-selective membranes.

3. Apparatus according to claim 1 in which said fluid permeable tubules are selected from the group consisting of membrane filtration, ultrafiltration and reverse osmosis tubules.

4. Apparatus according to claim 1 in which said means for applying a substantially direct current electrical potential comprises means for reversing the direction of the potential.

5. A process for transferring electrolytes from a first solution located in depletion spaces of an electrodialysis apparatus to a second solution located in enriching spaces of said apparatus, said depletion and enriching spaces being separated from each other by electrolytically conducting barriers, the process comprising:

(a) introducing fluid under pressure into the bore of a fluid permeable tubule, said tubule being positioned in at least one of the depletion spaces of said apparatus to cause at least part of said introduced fluid to permeate said tubule and pass into said depletion space;

(b) applying a substantially direct electric current to such apparatus to cause ions to migrate from said depletion space into said adjacently positioned enriching space; and

(c) withdrawing at least part of said first solution from said depletion spaces.

6. A process according to claim 5 in which the fluid introduced into said tubule is at least part of said first solution.

7. A process according to claim 5 in which the direction of the direct electric current is subsequently reversed.

8. Apparatus for transferring electrolytes from a first solution to a second solution, said apparatus comprising:

(a) a plurality of spaced electrolytically conducting barriers of a first kind, said barriers of a first kind having a transport number for ions of one sign substantially greater than that of said solutions, said barriers of a first kind being interspersed with spaced barriers of a second kind, said barriers of a second kind having a transport number for said ions of one sign substantially less than that of said barriers of a first kind, said barriers of a first kind and of a second kind defining depletion spaces and enrichment spaces therebetween;

(b) a fluid permeable tubule in at least one of said defined spaces;

(c) means for introducing fluid into said tubule;

(d) means for applying a substantially direct electric current to cause ions to leave said depletion spaces; and

(e) means for withdrawing fluid from said depletion spaces.