METHOD OF PURIFYING AQUEOUS COMPOSITIONS Russian patent published in 2015 - IPC C02F1/60 C02F1/58 C01B33/26 C02F1/469 

FIELD: chemistry.

SUBSTANCE: group of inventions can be used in membrane electrolytic production of chlorine and sodium hydroxide for removing silicon from aqueous compositions containing sodium chloride. The method includes adding, to an aqueous composition of sodium chloride containing silicon, an aluminium-containing compound to obtain molar content of aluminium higher than molar content of silicon in said aqueous composition; Monitoring and maintaining pH of the composition at a first level higher than or equal to 8 and lower than or equal to 10 to obtain a first precipitate; Monitoring and maintaining pH of the obtained aqueous composition at a second level higher than or equal to 4 and lower than or equal to 7 to obtain a second precipitate; separating the formed precipitate from the aqueous suspension to obtain a purified aqueous composition. According to the second version of the method, the precipitate is separated at each formation step thereof. A method of producing chlorine and sodium hydroxide includes electrolysis of aqueous sodium chloride solution purified from silicon using the disclosed methods using a membrane cell.

EFFECT: invention reduces content of silicon in the purified solution which contains sodium chloride, with aluminium content in the purified solution lower than 1 mg/l.

14 cl, 4 ex