Photocatalytic activity of tungsten-doped TiO2 with hydrothermal treatment under blue light irradiation

Tungsten doping and hydrothermal treatment were found to significantly improve the visible-light photoactivity of TiO2 synthesized by the sol-gel method. It was observed that TiO2 doped with a 0.5% W:Ti mole ratio and treated with 4 h of hydrothermal curing showed photoactivity under blue light irradiation equal to 74% of the commercial Degussa P-25 under UV irradiation, i.e., 0.01 mM 2-chlorophenol was completely removed in 120 and 90 min, respectively. Light absorptivity and photocatalytic activity under blue light irradiation were not dependent on the crystallite structure of the TiO2. The oxidation kinetics under blue light irradiation can be effectively explained by the Langmuir–Hinshelwood model with an apparent reaction rate constant and a Langmuir constant of 3.60 × 10−4 mM min−1 and 206.53 mM−1, respectively.