A study of photodegradation of sulforhodamine B on Au–TiO2/bentonite under UV and visible light irradiation

Au–TiO2/bentonite samples were prepared via deposition–precipitation method and calcined at different temperatures. These samples were characterized by X-ray diffraction (XRD), UV–vis diffusion reflectance spectroscopy (DRS), BET method, X-ray photoelectron spectroscopy (XPS) and TEM. The photocatalytic activities of the samples were tested by photodegradation of sulforhodamine B (SRB) under ultraviolet (UV) and visible light irradiation. The result showed that Au–TiO2/bentonite catalysts exhibited higher efficiency for mineralizing SRB than the well-known commercial TiO2 photocatalyst P25 in terms of COD changes. The most important advantage of Au–TiO2/bentonite over P25 was that it could be readily separated from aqueous suspensions by sedimentation after the reaction. It can maintain almost the same activity after being repeatedly used for 12 times. Possible mechanisms for SRB photoreaction in the presence of Au–TiO2/bentonite were proposed in this paper.

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