ABSTRACT:
Two photocatalyst composed of ZnO in the form of thin film adhered to a glass sheet but prepared using different coating techniques, i.e., metal evaporation ( M.EV) and sol-gel technique, have been examined for the photodegradation of 2,4,6-Trichlorophenol (TCP) in water in presence of UV irradiation at a wave length of 254 nm in the reactor was constructed of silica glass and air was continuously injected in the pollutant solution while continuous stirring. The concentration of TCP and its intermediate products was determined by HPLC at definite irradiation times. Simple first order kinetics was applied to the change of concentration of TCP as well as the CO2 evolved. Nevertheless, correlation of the types and concentrations of all intermediate products. In TCP degradation on the M.EV photocatalyst, decay with irradiation time gives complete disappearance of the intermediates after 60 min, whereas used the sol-gel catalyst, all intermediate products are either increase or even increase then remain unchanged as a function of irradiation time . Even though, the difference between the degradation rate of the initial pollutant (TCP) on the two current catalysts is not such great. The adsorption capacity (in dark) of TCP on the ME.V. catalyst was found to be fast at initial time, whereas it is gradual in case of the sol-gel catalyst. This fast adsorption can contribute to the higher activity of the ME.V. catalyst.