Kinetics and mechanism of TNT degradation in TiO2 photocatalysis

The photocatalytic degradation of TNT in a circular photocatalytic reactor, using a UV lamp as a light source and TiO2 as a photocatalyst, was investigated. The effects of various parameters such as the initial TNT concentration, and the initial pH on the TNT degradation rate of TiO2 photocatalysis were examined. In the presence of both UV light illumination and TiO2 catalyst, TNT was more effectively degraded than with either UV or TiO2 alone. The reaction rate was found to obey pseudo first-order kinetics represented by the Langmuir–Hinshelwood model. In the mineralization study, TNT (30 mg/l) photocatalytic degradation resulted in an approximately 80% TOC decrease after 150 min, and 10% of acetate and 57% of formate were produced as the organic intermediates, and were further degraded. NO−3 NO−2, and NH+4 were detected as the nitrogen byproducts from photocatalysis and photolysis, and more than 50% of the total nitrogen was converted mainly to NO−3in the photocatalysis. However, NO−3 did not adsorbed on the TiO2 surface. TNT showed higher photocatalytic degradation efficiency at neutral and basic pH.