Efficient photocatalytic elimination of Temephos pesticide using ZnO nanoflowers

Abstract

Temephos (Tem) is a widely used pesticide to control mosquito’s proliferation in tropical countries. This pesticide is put in stagnant water bodies where mosquitoes reproduce, killing larvae effectively. Recently, Tem has been identified as a DNA damaging agent; despite, people use it unmoderated in water reservoirs for personal consumption. Thus, Tem has become a hazard for human health and needs urgent attention. In order to reduce the risk of toxicity in those water sources we propose the use of nanostructured zinc oxide (ZnO) photocatalyst films to degrade this toxic compound. ZnO films with nanoflower morphology were prepared using a simple spray pyrolysis method. The band gap was 3.2 eV but a large number of natural defects present in the films allowed the absorption of visible light. The photocatalytic degradation ability of ZnO nanoflowers removed the toxic Tem under the illumination of a solar simulator. The UV–vis spectroscopy and High-Performance Liquid Chromatography analysis of Tem at regular intervals during photocatalysis confirmed the degradation of Tem, along with its transformation products or metabolites from water, reducing seven times the Tem half-life time in water. Total organic carbon measurements also indicated the mineralization of the compound.