Electrodialysis including filled cell electrodialysis (electrodeionization)

US5503729A · kind A · utility

Assignee

• Ionics, Incorporated · US

Inventors

• Irving D. Elyanow · Lexington, US
• Arthur L. Goldstein · Weston, US
• Russell James MacDonald · Watertown, US
• Wayne A. McRae · Zürich, CH
• Keith J. Sims · Framingham, US
• Li Zhang · San Diego, US

Key dates

• Filing date: Apr 25, 1994
• Grant date: Apr 2, 1996
• Expiry date: Apr 25, 2014

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C02F2201/46115
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

Electrodialysis ("ED") stacks are disclosed having components selected from the group: PA1 a) cation exchange ("CX") membranes and/or CX granules having in at least a surface a predominant amount of sulfonate exchange groups and a minor amount of weakly ionized exchange groups; PA1 b) anion exchange ("AX") membranes and/or AX granules having in at least a surface substantially only quaternary ammonium and/or phosphonium exchange groups which upon decomposition leave almost no amine or phosphine groups bound to the membranes or granules; PA1 c) AX and/or CX granules which are selective to monovalent ions at currents which are fractions of the limiting current of such granules; PA1 d) AX and/or CX membranes and granules, such membranes and granules selective to monovalent ions at currents which are fractions of the limiting current of such membranes and granules; PA1 e) ion exchange ("IX") granules in which the concentration of IX groups in the inner regions is a fraction (including zero) of the concentration in the outer regions; PA1 f) AX membranes and/or granules having in at least a surface AX groups having the formula ##STR1## where the R's represent substituents other than hydr…