Abstract

The aim of the present study is to investigate the activity of semiconductor materials on the degradation of pesticides cypermethrin under UV-light (6 W, ? = 354 nm). Three types of photocatalysts were prepared namely Zn/ZnO, Zn/ZnO/TiO₂ and Al/Al₂O₃­/TiO₂. Zn/ZnO film was prepared by anodic oxidation of zinc in NaOH with various concentrations (0.2, 0.3, 0.4, and 0.5 M) at 12 V for 20 minutes. The best concentration for NaOH is 0.5 M and the best applied voltage in the preparation of Zn/ZnO is 12 V. The Al/Al₂O₃ film was prepared by anodizing aluminium plate in H₂SO₄ at 12 V for 60 minutes. TiO₂ films were electrodeposited onto Zn/ZnO and Al/Al₂O₃ by electrolysis technique in (NH₄)₂[TiO(C₂O₄)] solution at 12 V for 20 minutes. Zn/ZnO/TiO₂/UV shows the highest photocatalytic degradation of cypermethrin compared to the other photocatalytic system. The effects of some operational parameters such as pH and oxidizing agent (H₂O₂) on the degradation efficiency of the semiconductor were also studied. The optimum pH for the photodegradation of cypermethrin using Zn/ZnO is pH 5. In the presence of H₂O₂ as the oxidizing agent, the overall reaction is significantly reduced due the scavenging effect of H₂O₂. The surface morphology of the catalyst was studied by FESEM analysis.

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