MANUFACTURE OF ALKALI METALLIC HYDROXIDE OF HIGH PURITY

摘要

PURPOSE:To increase the purity of alkali metallic hydroxide by keeping the flow rate of rising of an anolyte in an anode chamber at a prescribed value so as to carry out electrolysis without forming a vapor phase of gaseous halogen in the anode chamber. CONSTITUTION:An electrolytic cell is divided into an anode chamber 2 having an anode 4 and a cathode chamber 3 having a cathode 5 with a cation exchange membrane 1. An aqueous soln. 7 of alkali metallic halide is fed to the anode chamber 2 from an electrolytic soln. feeding inlet 9, and generated geseous halogen is taken out of a discharge outlet 11 as a mixture with the soln. 7. At this time, the flow rate of rising of the anolyte 7 in the anode chamber 2 is kept at >=0.5cm/sec so as to carry out electrolysis without exposing the membrane 1 to a vapor phase of gaseous halogen. Since gaseous halogen is not diffused into the cathode chamber 3 through the membrane 1, the concn. of alkali metallic halide in the chamber 3 is reduced, and alkali metallic hydroxide of high purity is obtd.