Zn/ZnO/TiO2 and al/aI203/TiO2 photocatalysts for the degradation of cypennethrin

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.