| 摘要 |
PURPOSE:To reduce electric power original unit by using the exchange membrane composed of three or more layers having the specific ion cation exchange groups and limiting the concentration of electrolyte at the time of electrolyzing NaCl, etc. in an electrolytic cell having the cation exchange membrane between cathode and anode. CONSTITUTION:While an aqueous alkali metal salt solution such as of NaCl is being maintained at 3.5-5N (particularly 3.5-4.5N with an aqueous NaCl solution) in concentration, it is electrolyzed under the conditions where the concentration of the aqueous NaOH solution being formed is 20-50% and yet water of 2- 5mol per Na<+> 1mol transmitting through the cation exchange membrane is carried using undermentioned cation exchange membrane as a diaphragm between both electrodes. Namely, the cation exchange membrane is formed by three or more layers of the layer having mainly sulfonic acid groups on the anode side and the plural layers having cation exchange groups of acidity weaker than that of said sulfonic acid groups (e.g., -CF2COOH, -CONH2, etc.). |
