A comparative study on reaction kinetic of textile wastewaters degradation by UV/TiO2 and UV/ZnO

A comparative kinetic study of photocatalytic degradation of textile wastewater by UV/TiO2 and UV/ ZnO for removal of chemical oxygen demand (COD), and color was carried out. The effects of some parameters such as the initial concentration of catalyst, initial COD concentration and light intensity on the photocatalytic process were also examined. It was demonstrated that the COD removal by TiO2/UV and ZnO/UV was about 49 %, 33.3 %, and color removal was 30 % and 10 %, respectively. The experiment demonstrated that the photo-degradation efficiency of TiO2 was significantly higher than that of ZnO. On the other hand, the kinetic study shows that decomposition of chemical oxygen demand follows a first-order for processes. The rate of degradation is highly dependent on the initial concentration of TiO2, ZnO and light intensity. A comparison between experimental and calculated degradation rate constants shows that TiO2/UV process gives better results than photocatalytic treatment. Maximum degradation rate was achieved for TiO2/UV at optimum concentrations of TiO2.