Photodegradation of Herbicide Dicamba with TiO2 Immobilized on HZSM-11 Zeolite

Photodegradation of dicamba, an ionizable herbicide, using TiO 2 supported on HZSM-11 zeolite was investigated. Four photocatalysts with different weight percentages (wt%) of TiO 2 were evaluated: 3%, 10%, 30% and 50%. The effects of the catalyst concentration, the initial pH value and the repeatability of the photocatalytic activity after multiple cycles of reuse were also evaluated. Results showed complete degradation of dicamba within 120 min with the TiO 2 /HZSM-11 (30 wt%) catalyst. Also, this catalyst is stable (no detectable leaching was observed), can be easily removed from treated solutions and it is reusable for at least nine consecutive cycles. An XRD analysis indicated that the TiO 2 /HZSM-11(30%) catalyst remained unchanged until the ninth cycle, when it was compared with a new catalyst. The results indicated that the addition of H 2 O 2 to the solution did not affect the catalyst structure. These are important advantages over unsupported TiO 2 , making it a good photocatalyst for the treatment of water courses polluted with dicamba.