The photocatalytic degradation in aqueous medium of the Alizarin Red S (ARS) dye using UV blacklight irradiation (λ = 365 nm) over sol–gel nickel-titania doped photocatalyst (0.5–6 wt% Ni) was investigated. The doped semiconductors were characterized by XRD, nitrogen physisorption and UV–Vis diffuse reflectance spectroscopy. High specific surface areas (90 m2/g) and small crystallite sizes, which varied with the Ni content, were obtained. No evidence concerning the formation of NiO was observed by XRD, which suggested the deposition of small NiO composites onto the TiO2 surface. A shift to the visible region of the Eg band gap was obtained by increasing the nickel content in the semiconductors. The substitution of some Ti4+ by Ni2+ cations during the preparation of the photocatalysts was proposed. It was found that the synthesis of the catalysts with 0.5, 1.5, 3 and 6 wt% of Ni resulted in semiconductors that were more active than P25 commercial titania in the photodegradation of ARS.
Dye removal from wastewater Ni-doped TiO2Alizarin Red S dye adsorption Sol–gel TiO2Alizarin Red S (ARS)