| 摘要 |
PURPOSE:To enhance the purity of produced aqueous sodium hydroxide solution by a method wherein anion nonpermeability is made lower at the part opposite the effective electrolytic surface of the anode than at the part not opposite the same surface, in a cylindrical cation exchange membrane in a finger type electrolytic tank. CONSTITUTION:The cation exchange membrane 1 opposite the effective electrolytic surface of the anode is jointed with the cation exchange membrane 3 not opposite the same surface, separated by a porous hydrophilic fluoric polymer membrane 2, then set to the cathode surface 7 using mounting frames 5. When a carboxylic acid type cation exchange membrane with equivalent weight of 1,000-1,800g is used as the membrane 1, and a sulfonic acid type cation exchange membrane with equivalent weight of 2,000g or more as the membrane 3, anions are prevented from passing through part of low current density in cylindrical membrane. |
