Photosensitized degradation of terbuthylazine in water

Article abstract of DOI:10.1016/0045-6535(96)00176-2

We investigated the photodegradation of terbuthylazine, an s-triazine herbicide, in the presence of hydrogen peroxide (H₂O₂), titanium dioxide (TiO₂), acetone or humic substances. In the presence of H₂O₂ and UV light, the degradation of terbuthylazine quickly leads to the formation of ammeline. The degradation pathway consists of dealkylation reactions giving 2-chloro-4,6-diamino-1,3,5-triazine, and then ammeline through hydroxylation. Irradiation of terbuthylazine with simulated solar light in the presence of titanium dioxide gives also dealkylation products in the first stage of degradation. Acetone at 1% (v/v) produces a 7-fold enhancement of the degradation rate. In the presence of humic substances, different results were obtained, depending on the origin of the substances tested. The humic acids isolated from a soil accelerate the degradation speed, whereas the fulvic acids from a small stream reduce it.