METHOD FOR ELECTROLYZING ALKALI METAL HALIDE

摘要

An improved method for electrolyzing alkali metal halide. Electrolysis is carried out by supplying an aqueous solution of a halide of alkali metal into an anode chamber partitioned by a cation-exchange membrane and water into a cathode chamber to obtain halogen from the anode chamber and hydrogen and alkali hydroxide from the cathode chamber. The cation-exchange membrane is a fluorocarbon polymer membrane which is prepared by arranging one side thereof to have a cation exchange group concentration lower by 10 to 30% within a depth range of 1 to 100.mu. than that of the remainder of the membrane. The anode chamber is prepared with this side of the membrane which has the lower cation exchange group concentration arranged to face the anode chamber. By this arrangement, a high purity alkali hydroxide can be manufactured at a high rate of decomposition of halide of alkali metal and at a high current efficiency.