EXPERIMENTAL ANALYSIS OF EFFICIENCY OF ELECTROCHEMICAL PROCESS OF PROCESSING WASTE WATER FOR PRODUCTION OF SODIUM BICARBONATE WITH PRODUCTION OF SODIUM HYDROXIDEN

The production of purified sodium bicarbonate is accompanied by the formation of wastewater containing sodium carbonate and bicarbonate. Up to 1.5 m(3) of wastewater is formed per 1 t of purified sodium bicarbonate. Wastewater contains about 23.5 g/l sodium carbonate and about 40.4 g/l sodium bicarbonate. The article presents the results of studies related to the processing of wastewater generated in the production of purified sodium bicarbonate in a membrane electrolyzer with a cation exchange membrane. The waste water treatment process was carried out at a membrane current density of 30 mA/cm(2) to 60 mA/cm(2). It is shown that in the process of electrochemical processing of wastewater, sodium carbonate is extracted first, and then sodium bicarbonate is extracted. At the same time, during the electrolysis, sodium hydroxide is formed. The maximum concentration of sodium hydroxide achieved in the process was 362 g/l. The current efficiency of the electrolysis process calculated by changing the concentration of sodium hydroxide depends on the membrane current density. The maximum current efficiency is observed at a current density of 30 mA/cm(2) and equals 64.3%. The specific energy costs of sodium hydroxide producing increase with increasing current density. The minimum energy consumption was 2.2 kWh/kg.