Hydrothermal synthesis spherical TiO ₂ and its photo-degradation property on salicylic acid

Anatase TiO ₂ spheres have been prepared using hydrothermal synthesis. The prepared spheres were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-vis diffuse reflectance spectra (UV-vis DRS). The TiO ₂ consisted of well-defined spheres with size of 3-5 μm. The photocatalytic activity of spherical TiO ₂ was determined by degradation of salicylic acid under visible light irradiation. It was revealed that the degradation rate of the spherical TiO ₂ which was processed at 150 °C for 48 h could reach 81.758%. And the kinetics of photocatalytic degradation obeyed first-order kinetic, which the rate constant value was 0.01716 S ^-1 of the salicylic acid onto TiO ₂ (temperature: 150, time: 48 h). The kinetics of adsorption followed the pseudo-second-order model and the rate constant was 1.2695 g mg ^-1 of the salicylic acid onto TiO ₂ (temperature: 150, time: 48 h).