| abstract |
A sodium chloride solution is electrolyzed to produce a high strength caustic solution and sodium chlorate solution, using two different electrolytic cells. In the first cell, a twocompartment cell in which the compartments are separated by a permselective membrane of a hydrolyzed copolymer of a perfluorinated hydrocarbon and a fluorosulfonated perfluorovinyl ether or of a sulfostyrenated perfluorinated ethylene propylene polymer, the sodium chloride solution is electrolyzed at a pH of about 4 to 7 to produce aqueous sodium hydroxide solution in the cathode compartment and chlorine and cell liquor containing chlorate in the anode compartment. Then, the cell liquor, already containing some chlorate, is further electrolyzed in a conventional chlorate cell or equivalent apparatus to convert chloride therein to chlorate. After separation of the chlorate from chloride present with it the chloride is returned to the first cell. |