Photocatalytic Degradation of Congo Red Dye on Thermally Activated Zinc Oxide

Abstract

Congo Red in aquatic system has been recognized as a serious problem in living organism because of its toxic nature and therefore, its degradation is highly essential. In the present work, the efficacy of thermally activated ZnO was studied for photo-catalytic degradation of Congo red (CR) dye. The batch operation was carried out by irradiating the aqueous solution of dye in the presence of semiconductor. The effect of various parameters such as catalyst loading, pH, oxidant dose, intensity variations and initial concentration of the dye on degradation was investigated. The maximum degradation capacity of ZnO for CR was found to be 11.8 mg g -1 at optimized condition (303 K, 60 min, pH (8), dose (0.05g)). The pseudo-second-order kinetic model described the CR degradation process with a good fitting. Thermodynamic parameters such as ΔH, ΔS, and ΔG were calculated, which indicated that the process was spontaneous and exothermic in nature, that was evident by increasing the randomness of the dye at the solid and liquid interface. The high CR degradation ability and regeneration efficiency of this photocatalyst suggest its applicability in industrial systems and data generated would help in further upscaling of the degradation process.