Photocatalytic decomposition of triclopyr over aqueous semiconductor suspensions

The photocatalytic degradation of 3,5,6-trichloro-2-pyridinyloxyacetic acid (Triclopyr), a pyridine analogue of the phenoxy herbicides, has been investigated in aqueous heterogeneous solutions containing TiO(2) or ZnO as photocatalyst. The disappearance of the organic molecule follows approximately a pseudo-first kinetic order according to the Langmuir-Hinselwood model. As mineralization products, CO(2) and Cl(-) ions have been identified, whereas the nitrogen atom forms only NH(4)(+) ions. Various commercial photocatalysts were compared with respect to their overall efficiency, as well as the production of CO(2). The effect of pH and H(2)O(2) on the reaction rate was ascertained. The photooxidation of Triclopyr has also been monitored with FTIR spectroscopy. (C) 1998 Elsevier Science S.A. All rights reserved.