Studies on the Oxidative Removal of Sodium Thiosulfate from Aqueous Solution

Thiosulfate is generated from various process industries, such as petrochemical, metallurgical, photography processing, pharmaceutical, pigment and dye manufacturing units, etc. Thiosulfate-bearing wastewater is also produced during the anaerobic treatment of wastewater. In the present work, oxidative removal of thiosulfate in the presence of UV light from aqueous solution has been investigated. The effect of thiosulfate concentration, oxygen partial pressure, UV light intensity and air flow rate on the kinetics of thiosulfate removal has been explored, and suitable rate equations were developed for the oxidation processes. 67 % of thiosulfate was removed from the aqueous solution by carrying out aerial oxidation for one hour. Using photooxidation by UV light, 1,200ppm thiosulfate could be oxidized by one hour. Overall reaction by aerial oxidation followed the second-order kinetics, whereas by photooxidation, it followed third-order kinetics.