Decolorization of Synthetic Dye by Photocatalytic Oxidation

Wastewater effluent from textile plants using various dyestuffs is one of the major water pollution sources to environment. Except for coloring receiving water bodies such as rivers and lakes, dyes also undergo chemical and biological changes that consume dissolved oxygen in the water bodies; some dyes even possess toxicity that is hazardous to aquatic life. Traditional methods for treating the textile dye wastewaters consist of various chemical, physical, and biological processes. More advanced combined chemical and physical treatment techniques include adsorption, electro coagulation, ultrasonic decomposition, advanced chemical oxidation, nanofiltration, chemical coagulation followed by sedimentation and so forth. Most of the treatment methods have disadvantages such as high cost, high energy waste, and generating secondary pollution during the treatment process. The photo catalytic process involving TiO₂ semiconductor particles under UV light illumination has been shown to be potentially advantageous and applicable in the treatment of wastewater pollutants for the last two decades. It is now considered as a promising technology for the treatment of organic contaminants in aquatic and atmospheric environments. It has a several advantages compared to the traditional treatment methods, it wont leave any residue to the environment and complete mineralization has been reported in most of the study. In order to treat the wastewater effluents from dyeing and finishing industries by an advanced oxidation process, the decomposition kinetics of organic dye by TiO2/UV was systematically studied in batch slurry reactors. The factors of study include agitation speed, effect of dye concentration and effect of TiO₂ dose and reuse potential of used TiO₂.