Methylene blue photodegradation over titania-decorated SBA-15

Santa Barbara Amorphous (SBA-15) mesoporous materials decorated with vary amount of TiO2 (7-31% TiO2/SBA-15) were prepared by the post-synthesis method from previously synthesized SBA-15 and their photocatalytic activity toward the degradation of methylene blue (MB) was measured. Nonionic surfactant was used as liquid template and tetraethyl orthosilicate (TEOS) as SiO2 precursor for the synthesis of mesoporous silica SBA-15. The synthesized x% TiO2/SBA-15 materials were characterized by N-2 adsorption-desorption isotherms, X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), micro-Raman spectroscopy, infrared spectroscopy of framework vibration (IR-KBr) and X-ray photoelectron spectroscopy (XPS). The x% TiO2/SBA-15 photocatalysts were found to be more active than pure anatase titania and this increase was linear with TiO2 loading. The highest activity of 31% TiO2/SBA-15 sample was explained in terms of the combined factors such as a high crystallinity of anatase phase, preservation of a high surface area, a large amount of the surface hydroxyl groups, and a larger accessibility of photo-oxidative sites. A linear correlation between the apparent first order rate constants (k(app)) and the amount of TiO2 species located within porous structure of the SBA-15 substrate was found. (C) 2011 Elsevier B.V. All rights reserved.