Synthesis of a New Mesoporous Material as a Photocatalyst for Degradation of an Organophosphorus Pesticide

The removal of persistent organic chemicals from water is a pressing ecological problem. Persistent contaminants include pesticides, solvents, detergents and a variety of industrial chemicals due to resistance to biodegradation are capable of penetrating deep into the soil and of reaching groundwater [1]. Because of the development of the agrochemical industry, the problem of pesticide pollution is increasing day by day. Chlorpyrifos is one of the world s most widely used organophosphorus insecticide in agriculture. It shows a wide spectrum of biological activity also it is used to control range and forage insect pests as well as soil-dwelling grubs, rootworms, borers and subterranean termites. [1] The greatest use of chlorpyrifos is in cotton, rice, corn, tobacco, almonds, beans, maize and fruit trees including oranges, bananas, apples, and vegetables. Symptoms of acute poisoning include headache, nausea, muscle twitching and convulsions and in some extreme cases even death [2]. Because of their health effects, it is necessary to use alternative technologies to remove pesticides from water. Among the latest technologies, photocatalysis is one of the most advanced and developed technology to eliminate pollutants from the environment [3]. In this study, Photocatalytic degradation of chlorpyrifos in aqueous media by using KIT-6/Fe3O4/WS2 nanocomposite under visible light irradiation was investigated. At the first, WS2 nanoparticles were dispersed on KIT-6 (three-dimensional mesoporous silica) by employing a hydrothermal method and then combined with Fe3O4 for easy separation after water treatment by applying an appropriate magnetic field. The synthesized nanocomposite was successfully characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR). The effect of several parameters such as photocatalyst amount, pesticide concentration, pH, radiation time, and temperature on the percentage of chlorpyrifos degradation were investigated and optimized. The degradation percent of chlorpyrifos was carried out using UV-Vis spectrophotometer. The results indicated that the synthesized nanocomposite exhibited a high efficient photocatalytic activity on the photodegradation of chlorpyrifos.