Photocatalytic Degradation of Imidacloprid by a Novel ZnO Based Nanocomposite: Synthesis Process and Degradation Pathways

Many kinds of pesticides released into the environment as a result of runoff from agricultural and urban areas cause pollution of soil, air, surface water, and groundwater and are harmful to human health [1]. Imidacloprid is a chloronicotinyl pesticide, commonly used in agriculture, arboriculture and in residential areas to control a variety of crop-damaging insects, termites, cane beetles, carpenter ants, flees and cockroaches. It acts as a neurotoxin. That is why; it is efficient even at very low concentrations. Its water solubility (0.61 g/L) is high as compared to other pesticides. Its photolysis t1/2 in water is 3-5 hours, and on the soil surface, the t1/2 is 39 days. However, because of its high solubility, it readily enters from water to soil where it is resistant to degradation. Its tolerance in food ranges from 0.02 - 3.0 mg/kg [2]. During the present study, the concentration of imidacloprid was determined by using a wavelength of 270 nm, where its most intense absorption was noted. A number of methods have been developed to remove the pollutants from the waters and wastewaters including adsorption, filtration, chemical oxidation and photocatalyst. The present study focused on synthesize of ZnO/CoMoO4/Poly Aniline nanocomposite and investigated the photodegradation of imidacloprid using this nanocomposite in aqueous solution under visible irradiation. The prepared nanocomposites were characterized by Scanning electron microscope (SEM), X-ray diffraction (XRD) measurements. Parameters such as time of visible irradiation (90 min), pH (9), pesticide concentration (10 ppm) and amount of nanocomposite (100 mg) were investigated. The results of the study revealed an increase in photodegradation of imidacloprid by ZnO/CoMoO4/Poly Aniline nanocomposites than simple ZnO. This nanocomposite was effective for imidacloprid degradation.: