The removal of Hexavalent chromium; (Cr (VI)) by ZnO/LECA as a nano photocatalyst using full factorial experimental design

Abstract

In this research, a synthesized nano photocatalyst was prepared by supporting ZnO nanoparticle on Lightweight expanded clay aggregate (LECA). The catalyst was synthesized by co-precipitation method. The SEM, FT-IR and XRD tests were used to characterize ZnO/LECA, which was employed for photocatalytic removal of Cr (VI) from aqueous solution in batch photoreactor. The full factorial experimental design (FFD) was used for the statistical analysis of data. The influence of catalyst amounts, pH, and initial concentration of Cr (VI) was investigated on the reduction of Cr (VI) to Cr (III). The number of active site was increased with increase in the concentration of catalyst to some extent. Also, the selection of other factors in optimized amount was important. The optimal conditions were obtained at 0.75 g/l of photocatalyst, pH at 5 and 20 mg/l of Cr(VI). The experimental and predicted reduction efficiency by FFD at optimal conditions were 97.6 and 96.18%, respectively. The comparison of experimental and predicted data showed a good agreement between them.