Enhanced photocatalytic efficiency of NiS/TiO2 composite catalysts using sunset yellow, an azo dye under day light illumination

Abstract To improve the solar light induced photocatalytic application performances of TiO 2 , in this study, the NiS modified TiO 2 composite photocatalysts with various ratios of NiS to TiO 2 were prepared by sol–gel method. The catalyst was characterized by X-ray diffraction (XRD), high resolution scanning electron microscope (HR-SEM), high resolution transmission electron microscope (HR-TEM), energy dispersive spectra (EDS), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (B–E–T) surface area measurement methods. The photocatalytic activity of NiS/TiO 2 was investigated for the degradation of sunset yellow (SY) in aqueous solution using solar light. The NiS/TiO 2 is found to be more efficient than prepared TiO 2 and TiO 2 –P25 at pH 7 for the mineralization of SY. The effects of operational parameters such as the amount of photocatalyst, dye concentration and initial pH on photo mineralization of SY have been analyzed. The degradation was strongly enhanced in the presence of oxidants such as H 3 K 5 O 18 S 4 (Oxone), KIO 4 , and KBrO 3 . The mineralization of SY has been identified by COD measurements. The catalyst is found to be reusable.