A comparative study of different porous amorphous silica minerals supported TiO2 catalysts

Three porous amorphous silica minerals, including diatomite, opal and porous precipitated SiO2 were adopted to prepare supported TiO2 catalysts by hydrolysis-deposition method. The prepared compound materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Through morphology and physical chemistry properties of the resulting TiO2/amorphous SiO2 catalysts, it was proposed that the nature of silica supports could affect the particle size and the crystal form of TiO2 and then further influence the photocatalytic property of TiO2/amorphous SiO2 catalysts. The catalytic properties of these porous amorphous silica supported photocatalysts (TiO2/SiO2) were investigated by UV-assisted degradation of Rhodamine B (RhB). Compared with pure TiO2 (P25) and the other two TiO2/amorphous SiO2 catalysts, TiO2/diatomite photocatalyst exhibits better catalytic performance at different calcined temperatures, the decoloration rate of which can be up to over 85% even at a relatively low calcined temperature. The TiO2/diatomite photocatalyst possesses mixed-phase TiO2 with relatively smaller particles size, which might be responsible for higher photocatalytic activity. Moreover, the stable and much inerter porous microstructure of diatomite could be another key factor in improving its activity. (c) 2013 Elsevier B.V. All rights reserved.