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

Photodegradation of dicamba, an ionizable herbicide, using TiO2 supported on HZSM-11 zeolite was investigated. Four photocatalysts with different weight percentages (wt%) of TiO2 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 TiO2/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 TiO2/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 H2O2 to the solution did not affect the catalyst structure. These are important advantages over unsupported TiO2, making it a good photocatalyst for the treatment of water courses polluted with dicamba.