PERFORMANCE RECOVERING METHOD FOR CATION EXCHANGE MEMBRANE FOR ALKALI CHLORIDE ELECTROLYSIS

摘要

PURPOSE:To recover the current efficiency of a deteriorated cation exchange membrane for electrolysis of alkali chloride to above the original performance by dipping the membrance in a water-mescible org. solvent followed by heat treatment, treatment with hydrochloric acid and dipping in an aq. soln. of NaOH. CONSTITUTION:A deteriorated perfluorocarbon type cation exchange membrane for electrolysis of alkali chloride is dipped in a water-miscible org. solvent having a b.p. above 120 deg.C under a press. below 760 mmHg, e.g. propylene glycol. The dipped membrane is then held between smooth plates such as glass plates, heat treated at 40-108 deg.C, treated with 0.05-10, esp. 0.5-8 N hydrochloric acid at 40-95, esp. 60-95 deg.C, and dipped in an aq. soln. of NaOH to recover the membrane performance. The membrane is produced as follows: for example, one side alone of a film of a copolymer of CF2=CF2 and CF2=CFOCF2C(CF2)FO- CF2CF2SO2F is contacted to ethylene-diamine, and Teflon fiber is introduced into the film, which is then heat treated and hydrolyzed.