| 摘要 |
PURPOSE:To obtain efficiently an aqueous alkali hydroxide soln. of high purity with high current efficiency by carrying out electrolysis under specified conditions in a three-chamber type electrolytic cell provided with two cation exchange membranes. CONSTITUTION:An electrolytic cell is divided into anode, intermediate and cathode chambers by placing two cation exchange membranes between anode and cathode. An aqueous alkali chloride soln. is fed to the anode chamber, and water or a dil. aqueous alkali hydroxide soln. is fed to the cathode chamber. An aqueous alkali hydroxide soln. is fed to the intermediate chamber, and electrolysis is carried out to obtain an aqueous alkali hydroxide soln. in the cathode chamber. At this time, the concn. of Cl<-> in the intermediate chamber is kept at <=10g/l. OH<-> migrated from the cathode chamber is associated with cations migrated from the anode chamber in the intermediate chamber, and the resulting alkali hydroxide, that is, the outlet soln. in the intermediate chamber is prevented from flowing into the cathode chamber. Alkali hydroxide produced in the cathode chamber is taken out as a product. By this method the desired product having a very low concn. of salt is obtd. |
