Performance of Graphene Nanomaterial for Removal of Organophosphate Pesticide from Aqueous Solutions

In recent years, water pollution and pesticide residues in food chain have become a seriousenvironmentalproblem [1]. Diazinon is a widespread organophosphorus pesticide which is usedto control a variety of insects in agricultural applications and household environments [2].This pesticide is known as a major contaminant in aquatic systems due to its potential toxicityto human and animals. Therefore, it is essential to remove from contaminants water [3]. Grapheneoxide was prepared from the oxidation of graphite powder by a strong acid by Hummers-Offemane method [4]. Then these particles were decorated with zinc oxide in two steps[5]. Afterwards scanning electron microscopy, X-ray diffraction and Fourier-transform infraredspectroscopy were used to investigate morphological changes and chemical structure ofthe prepared adsorbent. At a regular time-interval, samples were taken, centrifuged and analyzedspectrophotometrically at absorption peak (245 nm) of diazinon. The effect of variousparameters such as pH, contact time, diazinon concentration, temperature and adsorbent dosageon the process was investigated. The efficiency of removal of diazinon by applying optimalTaguchi conditions was 92% which include the contact time = 30 min, pH = 6.5, amountof sorbent = 15 mg and T = 20 °C. Accordingly, we concluded that GO/ZnO removed diazinonfrom aqueous solution to a great extent. The ability to remove this nanoparticle was alsoperformed on chlorpyrifos (organophosphorus halogenated toxins) under the same experimentalconditions of diazinon and the removal efficiency was 86%. So it was found that synthesizednano particles would be an appropriate adsorbent for eliminate the pesticide fromcontaminated water source.