Photoreduction of Cr(VI) in water using BiVO4-Fe3O4 nano-photocatalyst under visible light irradiation

Cu/N-codoped TiO2 prepared by the sol-gel method for phenanthrene removal under visible light irradiation

Cu/N-codoped TiO₂ nanoparticles were prepared by the modified sol-gel method, to study its efficiency for the removing of polyaromatic hydrocarbon (phenanthrene) from an aqueous solution. Urea and copper sulfate pentahydrate were used as sources of doping element for Cu/N-codoped TiO₂, respectively. The characterizations of the nanoparticles were done by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectra. XRD revealed that all the nanoparticles were indexed to the anatase phase structure, with crystallite size range from 11 to 30 nm, which decreased with the doping of copper and nitrogen. The photocatalytic activities of Cu/N-codoped TiO₂ showed the highest activities than other TiO₂ nanoparticles (TiO₂ and N-doped TiO₂). The photodegradation efficiency of Cu/N-codoped TiO₂ on phenanthrene under visible light irradiation was slightly higher (96%) comparing to UV light irradiation (94%). Cu/N-codoped TiO₂ was found to be very efficient and economical for phenanthrene removal, because the smallest amount of Cu/N-codoped TiO₂ exhibited the best removal efficiency on phenanthrene.

In situ preparation of highly stable polyaniline/W18O49 hybrid nanocomposite as efficient visible light photocatalyst for aqueous Cr(VI) reduction

In the present study, we prepared novel polyaniline supported W₁₈O₄₉ (PANI/W₁₈O₄₉) nanocomposite by in situ oxidative polymerisation method. We herein focused on enhancing the stability and the photocatalytic performance of W₁₈O₄₉. The prepared PANI/W₁₈O₄₉ was thoroughly characterized by FTIR, TEM, XRD, BET, UV-vis DRS and PL. The PANI support presented a great effect on the light harvesting and photo-charge transfer of the W₁₈O₄₉, and the optimum percentage of was found to be 10 wt%. As for treating Cr(VI), the effect of important water quality parameters (such as pH, ions, NOM, DO, temperature and SOAs) on photocatalytic performance was investigated under the visible light irradiation (λ > 420 nm). SOAs were shown to exert a dramatic accelerating influence on Cr(VI) reduction in the system. The obtained 10%-PANI/W₁₈O₄₉ can completely catalytically reduce 1 mM Cr(VI) in the presence of tartaric acid (1:3) within 50 min. Meanwhile, it can be recycled at ten times without any loss of photocatalytic efficiency, indicating the high stability of the as-prepared photocatalyst. The results of the study demonstrate the potential of the new obtained photocatalyst in efficient utilization of solar energy for treating aqueous Cr(VI).