Photodecolorization of Rhodamine B on tungsten-doped TiO₂/activated carbon under visible-light irradiation
2012
Li, Youji | Zhou, Xiaoming | Chen, Wei | Li, Leiyong | Zen, Mengxiong | Qin, Shidong | Sun, Shuguo
Tungsten-doped TiO₂/activated carbon catalysts have been prepared by a supercritical-pretreatment-assisted sol–gel process. The structural features of the photocatalysts have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV/Vis diffuse-reflectance spectroscopy (DRS), electron dispersive X-ray (EDX), photoluminescence spectroscopy, and Brunauer–Emmett–Teller (BET) analysis. The results revealed that a W–TiO₂ layer was coated on the AC surface, and had higher surface area and smaller crystallite size than TiO₂/AC obtained by a similar route. The W dopant was responsible for narrowing the band gap of TiO₂ and shifting its optical response from the ultraviolet (UV) to the visible-light region. The photocatalytic performances of the supported catalysts have been evaluated for the degradation of Rhodamine B (RhB) solution under visible-light irradiation. Compared with bulk W–TiO₂, the photoactivity was obviously enhanced when it was coated onto AC. In addition, it was found that the reactivity showed a significant relationship with the amount of W dopant, and the photoactivity order of the catalysts from weak to strong showed good agreement with their PL intensities. The effects of TiO₂ content, tungsten ion content, catalyst amount, pH, and initial RhB concentration have been examined as operational parameters. The photocatalytic reactions followed pseudo-first-order kinetics and are discussed in terms of the Langmuir–Hinshelwood model.
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