Effects of pH, temperature and various anions on thiourea disappearance inaqueous media with titanium dioxide under UV-irradiation. Photomineralization kinetics

Disappearance of thiourea in aqueous suspensions of TiO2 or ZnO occurs unde r near-UV irradiation. The effects of some parameters such as initial conce ntration of thiourea, temperature, pH and common inorganic anions were exam ined. The results indicate that tile process follows the Langmuir-Hinshelwo od type kinetics. In the presence of anions such as nitrates, chlorides and sulfates, the initial disappearance rate of thiourea at pH 6 drops. It is found that the initial rate of thiourea disappearance increases when temper ature of reaction mixture increases. Finally, kinetics of thiourea photomin eralization to nitrite, nitrate, sulfite and sulfate are established.