Synthesis and photocatalytic activity of V-doped mesoporous TiO2 photosensitized with porphyrin supported by SBA-15

Abstract

A highly efficient photocatalyst was produced by immobilizing V-doped mesoporous TiO2/tetrakis(4-carboxyphenyl)porphyrin (V-TiO2/TCPP) onto SBA-15 walls, and was then investigated for photodecomposition of 2,4-dichlorophenol (2,4-DCP) in aqueous solutions. In the present paper, first, in order to activate titanium dioxide by visible light, the TiO2 mesoporous was doped by vanadium (V-TiO2) and then it was sensitized by tetrakis(4-carboxyphenyl)porphyrin (TCPP). To improve the photocatalytic activity of the prepared catalyst, SBA-15 was functionalized with the prepared V-TiO2/TCPP by pre-anchorage of 3-(aminopropyl)-triethoxysilane via post-synthesis method (V-TiO2/TCPP/SBA). The obtained materials were characterized by UV–Vis absorption, FT-IR spectroscopy, diffuse reflectance (DRS), scanning electron microscopy, X-Ray diffraction, and N2 adsorption–desorption. Furthermore, a comparative study on the photodegradation of 2,4-DCP between V-TiO2/TCPP/SBA and V-TiO2/TCPP composites was performed and the role of SBA-15 was investigated. The results showed that the decomposition efficiency of the 2,4-DCP by using the V-TiO2/TCPP/SBA was much more than that of applying TCPP/V-TiO2 in high initial concentration of pollutant (up to 99 % in 300 mg/L). In addition, the photocatalytic degradations of 2,4-DCP using above photocatalysts all followed a first-order kinetic model. The V-TiO2/TCPP/SBA was recycled four times without significant loss of photocatalytic activity.