| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of preparing an aqueous potassium hydroxide solution having a low sodium content for medicament, food and semiconductor field, etc. SOLUTION: A crude aqueous solution of a concentration of 22 to 28% is prepared by mixing an aqueous potassium chloride solution of a sodium content <=1,500 ppm or water with a raw material potassium chloride of a sodium content 300 to 5,000 ppm. This solution is cooled to -5 to 10 deg.C to allow the solid potassium chloride to deposit and is subjected to separation of solid from the liquid to dissolve the potassium chloride in the water and thereafter the aqueous saturated potassium chloride solution of the sodium content below 60 ppm is prepared. The aqueous potassium hydroxide solution of the sodium content below 100 ppm when converted to the aqueous potassium hydroxide solution of a concentration 48% is obtained by electrolyzing the solution by an ion exchange membrane electrolysis method.
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