Influence of process parameters on the photodegradation of synthesized azo pyridone dye in TiO2 water suspension under simulated sunlight.

Photocatalytic degradation of synthesized azo pyridone dye (5-(4-sulpho phenylazo)-6-hydroxy-4-methyl-3-cyano-2-pyridone), in aqueous solutions by simulated sunlight in the presence of commercial TiO(2), Aeroxide P25, was studied. The reaction kinetics analysis showed that photodegradation exhibits pseudo first-order kinetics according to Langmuir-Hinshelwood model. The effects of various process parameters on the photocatalytic degradation were investigated. The optimal catalyst content and pH were determined. A decrease in the reaction rate was observed upon the increase of the initial dye concentration. Degradation of the dye was enhanced by hydrogen peroxide, but it was inhibited by ethanol. The influence of temperature was studied, and the energy of activation was determined. According to total organic carbon (TOC) analysis, 54% of TOC remained when 100% of the dye was decolorized. Although the intermediates were not determined in this study, the TOC results clearly indicate their presence during the reaction. In addition, photocatalytic degradation of simulated dyehouse effluents, containing tested azo pyridone dye and associated auxiliary chemicals was investigated.