A new acidic Ti sol impregnated kaolin photocatalyst: synthesis, characterization and visible light photocatalytic performance

In this study, a photocatalyst with visible light photocatalytic activity was obtained using raw materials, including commercial TiO2, sulfuric acid, and calcined kaolin (CK). The photocatalyst was prepared via a dissolving/impregnating process, in which acidic Ti sol was obtained by initially dissolving TiO2 particles in sulfuric acid, and then using the sol as impregnant for the CK. The prepared photocatalyst had wide spectral region and narrow band gap. In addition, the impregnation can create acid sites on the obtained composite surface and consequently improve the activity. A series of tests was performed to characterize the properties of the prepared samples. The visible light photocatalytic degradation of methyl orange (MO) in an aqueous solution was used as a probe reaction to evaluate the photocatalytic activities of the obtained samples. Under visible light irradiation, approximately 80 % of MO (with initial concentration of 20 mg/m3) was degraded in 3 h on the photocatalyst prepared by impregnating CK in acidic Ti sol, which was obtained using approximately 60 % H2SO4 solution followed by calcination at 400 °C. The acidity of the photocatalyst is the main factor that affects the catalytic activity of the photocatalytic degradation of MO.