Photocatalytic Degradation of Reactive Green-19 Dye Using Nano ZnO Catalyst

Abstract

The present work investigates the ZnO nanoparticles synthesis by using sol-gel method. The characteristics of the produced nano ZnO were examined using X-ray diffraction (XRD) technique. The study aims to achieve photocatalytic degradation of (RG-19) reactive green dye in aqueous solution containing nano ZnO as the photocatalyst using batch reactor system. An endeavor has been made to investigate the effect of pH, ZnO dose, irradiation time, RG-19 concentration, H2O2 addition, and light intensity on the treatment process. The tests were accomplished by subjecting the RG-19 aqueous solutions containing nano ZnO to the UV irradiating. The concentrations of RG-19 before and after treatment was measured spectrophotometrically. The extent of decolorization reached to 100% under optimal conditions after 160 minutes of irradiation. The ideal pH for the photocatalytic decolorization of RG-19 dye within the existence of nano ZnO is pH 8. Optimum nano ZnO dose was 800 mgL-1. Photocatalytic decolorization was directly proportional to initial RG-19 concentration and inversely with increasing temperature. The oxidizing agents (H2O2) improve the rate of decolorization. However, more addition of H2O2 decreases the decolorization rate. pseudo-first-order kinetics was followed for the decolorization process of RG-19 dye. An Arrhenius plot displays that the activation energy is equal to 7.855 kJmol-1 and the reaction is endothermic in nature.