Functionalization of bauxite tailing waste into supported ZnO as photocatalyst for dyes removal

An innovation to minimize environmental fate of bauxite tailing waste by conversion into tailing waste supported-ZnO is key concept developed in this research. The tailing waste-supported ZnO (ZnO/TW) materials were prepared dispersing metal precursor and in detail, investigation on effect of the preparation procedure: coprecipitation and hydrothermal was evaluated by physicochemical characterization using x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and diffuse reflectance UV-Visible spectrophotometry (UV-DRS). The prepared samples were examined to be photocatalyst for methyl violet (MV) degradation in photocatalytic oxidation under visible light exposure. The results showed the successful formation of dispersed into tailing waste support. The crystallite size of ZnO in the composite was influenced by preparation procedure which the hydrothermal gave lower size (30.58 nm) compared to that of prepared by the coprecipitation procedure (49.92 nm). Consequently, the hydrothermal prepared nanocomposite showed a higher band gap energy (3.18 eV), while the coprecipitation method produced nanocomposite with a band gap energy of 2.60 eV. The supporting ZnO contributed to enhanced specific surface area of the materials which in detail, the coprecipitated procedure exhibited higher specific surface area (156.32 m 2 /g) compared to that of hydrothermal procedure (119.05 m 2 /g). These optical and textural properties are responsible for the photocatalytic activity, as confirmed by the kinetics of MV adsorption using the prepared materials. The optimal degradation efficiency of MV of 98.82% was exhibited by the material prepared using coprecipitation method, and the material showed recyclability until 3rd usage.