Photocatalytic Degradation of Rhodamine B Dye in Wastewater Using Gelatin/CuS/PVA Nanocomposites under Solar Light Irradiation

Abstract

The crosslinked gelatin/CuS/PVA nanocomposite catalyst prepared using gamma irradiation as initiator was extensively characterized using several techniques including transmission electron microscopy (TEM), UV-Vis spectroscopy, infrared spectroscopy (IR) and X-ray diffraction (XRD). We chose Rhodamine B (RhB) dye as a model contaminant in order to investigate its Photocatalytic activity under solar light irradiation. The effects of pH, catalyst concentration and RhB concentration on degradation reaction were also investigated. Similar to the observed trend for the photocatalytic oxidation of other organic compounds, the efficiency of photocatalytic degradation of RhB tended to decrease with increasing the concentration of RhB. The degradation efficiency of RhB is found to increase as pH is increased up to pH of 10, then starts decreasing at pH values higher than 10. The degradation efficient of RhB is found to increase as the amount of the catalyst dosage increases up to an optimum value of 0.25 g. Increasing the concentrations of photocatalyst beyond 0.25 g was found to decrease the photocatalytic activity of RhB. It was proven that the degradation process of RhB reaction rate obeyed a pseudo-first-order reaction of the catalyst concentration of gelatin/CuS/PVA nanocomposite. The degradation kinetics was found to fit well Langmuir-Hinshelwood rate law. The results obtained showed that after using the catalyst five times repeatedly, the catalyst retained its efficiency and the rate of the degradation process was still above 80%.