Synthesis of zinc oxide photocatalysts from zinc-dust waste for organic dye degradation

Zinc-dust waste from a hot-dip galvanizing plant in the metal plating industry was successfully used as the starting material to synthesize zinc oxide (ZnO) nanopowder via a hydrothermal method. Effects of acid types in zinc-dust dissolving process and concentration of NaOH for precipitation on physical characteristics and photocatalytic activity of the synthesized ZnO were investigated. Elemental composition, phase and crystallite size, morphology with chemical composition, and specific surface area of the ZnO nanostructures were characterized by X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), and gas adsorption-desorption analysis, respectively. The photocatalytic performance of the prepared ZnO was evaluated by photodegradation of rhodamine B (RhB) under UV light irradiation. The ZnO nanostructures synthesized by dissolving zinc-dust with nitric acid, then precipitating with a solution of 6 M NaOH, and hydrothermal treatment at 170℃ for 8 h exhibited the highest dye degradation efficiency. It is up to 89.7% after UV irradiation for 240 min, which is comparable to the degradation efficiency of a commercial ZnO nanoparticles (92.7%). This work offers materials and synthesis method for alternative photocatalysts prepared from industrial waste that possess high photocatalytic activity for organic dye degradation.