| 摘要 |
PURPOSE:A high current-efficiency, low-voltage electrolysis of aqueous alkali chloride is conducted to provide alkali hydroxide of low concentration and Cl2 by using a modified membrane. The process utilizes a partially modified surface layer of a fluorine-containing, cation-exchange membrane whose ion-exchange ability is based on COOH group and which has a particular ion-exchange capacity. CONSTITUTION:A surface treatment is conducted on a fluorine-containing, cation- exchange membrane having an ion-exchange capacity of 1.3 to 2 (preferably 1.4 to 1.7) milliequivalent/one gram of dry resin, and having COOH group as an ion- exchange group. To treat the membrane surface in thickness of 0.1 to 50 (preferably 0.5 to 10) microns, an aqueous alkali hydroxide solution of 45% or higher concentration at 80 deg.C or above is used for a period of 30 min. to 48 hrs. (preferably 2 to 16 hrs.) to provide the surface ion-exchange capacity of 1.1 to 1.3 (preferably 1 to 1.2) milliequivalent/one gram of dry resin. If the surface that faces the cathode is modified by treatment, a more advantageous aspects in current-efficiency and voltage can be obtained.
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