Generation Characteristics of Chlorate and Perchlorate in Electrolysis of Salt Water Using Six Anodes of Different Materials

Abstract

Chlorate and perchlorate are oxidized substances of chloride, and they exist in the form of anions in water and toxic contaminants that should be controlled, especially in drinking water. To control and minimize the formation of perchlorate in the water purification process, the formation of chlorate and perchlorate in chlorine generation process was studied in electrolysis of salt water. Six electrodes with different properties (main components: A: RuO₂-TiO₂; B: RuO₂-IrO₂-TiO₂; C: IrO₂-SnO₂; D: IrO₂-Pt; E: Pt; and F: PbO₂) were tested. Electric voltage differed among electrodes and the generation of chlorate and perchlorate depended on their electric voltage. When electric current is constant, those electrodes of higher terminal voltage generally showed lower production of chlorine and higher generation of chlorate and perchlorate. It is noted the electrodes, E: Pt and F: PbO₂ are prominent in the generation of chlorate and perchlorate. Therefore, the generation of chlorate and perchlorate should be controlled with the consideration of electrode material, the especially in on-site generation of hypochlorite, industrial electrolysis, water purification devices, and hypochlorite generation devices that involve electrolysis.