Catalytic decolorization of Rhodamine B by combined process of SBE/ZnO and O3/UV: Optimization using response surface methodology

SBE (Spent Bleaching Earth) is a waste from palm oil processing that contains active SiO2 and Al2O3 which has adsorption capability, therefore often studied to be used in wastewater treatment. Nevertheless, due to the relatively low surface area, further treatment of SBE such as activation and combination with other materials is often required prior to its utilization. In this study, a composite of SBE/ZnO is applied in an advanced oxidation process using O3/UV to achieve a catalytic degradation of Rhodamine B dye. The experimental design employ response surface methodology to obtain the optimum operating condition of the decolorization process. The variables applied were pH (3, 5, 7), catalyst dose (0.2, 0.5, 1, g/L) and UV light intensity (0.13, 0.15, 0.17 mW/cm2). The experiments were performed on a lab-scale and batch reactor using a dye solution of 100 mg/L. The results showed that the optimum pH, catalyst dose, and UV intensity were 5, 0.5 g/L, and 0.15 mW/cm2, respectively. This condition resulted in the removal of Rhodamine B up to 99.87%.