Removal of Direct Red Dye 23 from Water and Wastewater Using S2O8 Oxidant Activated by UV Irradiation:An Investigation on the Operational Parameters

Document Type: Research Paper



The photo-oxidative decolorization of Direct Red 23 (DR23), a textile dye which is suspected to be carcinogenic was investigated using peroxydisulfate activated by UV irradiation and heat in a batch photo-reactor at experimental conditions. A very simple analytical method, direct UV–vis spectrophotometric detection, was utilized for the progress of photo-oxidative decolorization of dye in aqueous medium. The effect of operational parameters namely initial peroxydisulfate concentration, pH and temperature of reaction, additional photo-catalyst on the decolorization rate was truly investigated. The results showed that use of UV/S2 O8 2- system was a highly effective way to remove colored components from contaminated waters. Optimum conditions for maximum degradation was acidic pH (pH=2), temperature of 50°C with 7.5 mM of peroxydisulfate. Also, it was observed that dye degradation was enhanced using nano-TiO2 glass beads as photo-catalyst and peroxydisulfate consumption was significantly reduced to achieve the same percentages of dye degradation which was observed in UV/S2 O8 2- system at the same conditions.