Production of sodium hypochlorite by ground water electrolysis

Summary

Possible using groundwater to prepare a disinfecting chemical – sodium hypochlorite – has been considered. The use of natural water containing chlorides provides for eliminating the purchase of table salt and reducing the cost of the finished product by up to 40%. However, due to significant differences in the composition of natural waters, particularly, related to the concentration of chloride ions, the electrolysis of mineralized water can occur in an inefficient zone with high power consumption and low yield of active chlorine. On the territory of the Municipal Enterprise «Azovvodokanal» (Azov, Rostov region) an electrolysis plant is located with a capacity of 500 kg/day as active chlorine. The raw material for the production of sodium hypochlorite is mineralized groundwater. In the course of studies, the optimal conditions for the electrolysis of groundwater were established in order to determine the maximum current efficiency by chlorine with the minimum energy consumption. The studies were carried out using direct electric current in a flow-through mode at a current density of 10, 50, 100, 200, 500, 800 and 1000 A/m², and an initial solution temperature of 18–22°С. The working areas of the anode and cathode were 0.0022 m² each. The range of flow rates studied varied from 0.36 to 4.8 l/h, which corresponded to an electrolysis time of 3.5–0.26 min. The pH value during electrolysis ranged from 8.8 to 9.5. As a result of the studies, dependencies were obtained that characterize the parameters of the direct electrolysis of ground mineralized water.

Key words

water disinfection , membraneless electrolysis , low-concentrated sodium hypochlorite , direct electrolysis of ground water