The enhancement of adsorption and photocatalytic activity of rare earth ions doped TiO2 for the degradation of Orange I

Abstract Rare earth ions (Sm 3+ , Nd 3+ , Pr 3+ ) doped TiO 2 (RE 3+ –TiO 2 ) catalysts were prepared by the sol–gel method, and characterized by X-ray diffraction (XRD) and diffuse reflectance spectroscopy (DRS). The adsorption abilities and photocatalytic activities of RE 3+ –TiO 2 were evaluated by isothermal adsorption and Orange I degradation under UV light and visible light illumination. The adsorption results showed that RE 3+ –TiO 2 had higher saturated adsorption amounts and higher adsorption equilibrium constants than pure TiO 2 . The adsorption equilibrium constants ( K a ) and the saturated adsorption amount ( Q max ) of RE 3+ –TiO 2 would increase with the increase of dosage. In the meantime, the photocatalytic activity of RE 3+ –TiO 2 for Orange I degradation under both UV and visible light irradiations were higher than that of TiO 2 . The optimal dosage was 1.5% for Orange I degradation under UV light and 1.0% under visible light. The higher photoactivity might be attributable to the transitions of 4f electrons of RE 3+ .