Abstract
This study reported Fe doped zinc oxide (Fe-ZnO) synthesis to degrade chlorpyrifos (CPY), a highly toxic organophosphate pesticide and important sources of agricultural wastes. Fourier transform infrared, X-ray diffraction, scanning electron microscope, and energy-dispersive X-ray spectroscopic analyses showed successful formation of the Fe-ZnO with highly crystalline and amorphous nature. Water collected from agricultural wastes were treated with Fe-ZnO and the results showed 67% degradation of CPY by Fe-ZnO versus 39% by ZnO at 140 min treatment time. Detail mechanism involving reactive oxygen species production from solar light activated Fe-ZnO and their role in degradation of CPY was assessed. Use of H2O2, peroxydisulfate (S2O82−) and peroxymonosulfate (HSO5−) with Fe-ZnO under solar irradiation promoted removal of CPY. The peroxides yielded hydroxyl (OH) and sulfate radical (▪) under solar irradiation mediated by Fe-ZnO. Effects of several parameters including concentration of pollutant and oxidants, pH, co-existing ions, and presence of natural organic matter on CPY degradation were studied. Among peroxides, HSO5− revealed to provide better performance. The prepared Fe-ZnO showed high reusability and greater mineralization of CPY. The GC-MS analysis showed degradation of CPY resulted into several transformation products (TPs). Toxicity analysis of CPY as well as its TPs was performed and the formation of non-toxic acetate imply greater capability of the treatment technology.
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•Fe doped ZnO was successfully synthesized by sol-gel method.•Fe doping and use of peroxides synergistically promoted performance of ZnO.•Degradation of chlorpyrifos was inhibited by hvb+ and OH scavengers.•Second-order rate constants of chlorpyrifos with OH and ▪ were calculated.•Toxicities of chlorpyrifos and its transformation products were estimated.