Cobalt oxide-Zinc oxide nanocatalysts loaded on activated carbon for the photocatalytic degradation of methylene blue dye in water

Water contamination with organic dyes like methylene blue (MB) becomes among the main issues at the present time owing to their carcinogenicity and toxic nature towards ecology and human health. Thus, the removal of MB from water using adsorption-photocatalytic degradation method become promising due to its potential to convert this contaminant into non-harmful products. Wastewater containing MB micropollutants can be treated by photocatalytic degradation that involves the application of light and a photocatalyst to break down this dye into less harmful substances. Here, we report cobalt oxide-Zinc oxide (Zn/Co ₃ O ₄ ) binary nanocomposite supported on the activated carbon (AC) phoyocatalyst was prepared from the renewable agricultural solid waste (coffee husk) to break down MB in water bodies. The photocatalyst’s optical band gap, average crystalline size and functional groups were characterized by using UV-vis, XRD and FTIR techniques, respectively. The adsorption-photocatalytic degradation of the MB was studied at the optimum experimental parameter values of pH 10, initial concentration of dye of 10 mg/L, catalyst dose of 80 mg and contact time of 120 minutes. Under optimized conditions, the photocatalytic degradation efficiency of MB is 96.16% for ZnO/Co ₃ O ₄ /AC (1:2:2 mass ratios). Furthermore, the light assisted catalytic degradation of MB revealed that the use of AC as support for ZnO/Co ₃ O ₄ greatly improved the overall performance of the nanocatalyst against MB. This implies that the photocatalytic activities based on the ZnO/Co ₃ O ₄ /AC nanocomposite showed better photo-catalytic efficiency for the target MB dye. The prepared nanocatalyst is renewable and promising for further applications in the future.