PROCESS FOR PURIFYING CAUSTIC SODA LIQUORS

摘要

The invention relates to a process for purifying caustic soda liquors resulting from the sodium chloride electrolysis by chemical treatment, in a first step, with an oxidant, preferably sodium persulphate, in a ratio of 5g/l of liquor and hydrated baryta in a ratio of 4g/l of liquor, while stirring for 8...12 hours at the ambient temperature, followed by a second step of treatment with a sodium carbonate solution in a ratio of 40g/l of liquor, under the same temperature conditions while stirring for 4...7 hours. After resting for 10...14 hours, the purified solution is filtered through a glass wool filtering layer. The resulting caustic soda solution has a concentration of 14...45%, varying with the amount of distilled water used in both treatment steps.