Photocatalytic degradation of bentazon by TiO2 particles

The degradation of 3-isopropy1–2,1,3-benzothiadiazin-4-one-2,2-dioxide, the herbicide bentazon, by AMI simulated sunlight has been investigated in the presence of aqueous suspensions of TiO2. The half-life of the degradation process is ca. 30 minutes at pH=2 and ca. 4 minutes at pH=7 in the presence of 0.5 g L−1 of TiO2. The near quantitative recovery of sulfate ions and CO2 as well as the variation with time of dissolved and adsorbed organic carbon suggest that the process leads to complete mineralization of the herbicide. The process is extremely efficient even at very low concentration: in fact irradiation of 20 ppb of bentazon in the presence of 50 ppm TiO2 allows to recover < 0.1 ppb after 10 minutes.