Sol-gel synthesis- of TiO_2 nanoparticles and photocatalytic degradation of methyl orange in aqueous TiO_2 suspensions

摘要

Anatase TiO_2 nanoparticles of about 16 nm in crystal size have been successfully synthesized via a sol-gel method. Thermal treatment of the precursor at 500-600 deg C results in the formation of different TiO_2 phase compositions. The samples were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Effects of the pH value of the solution, H_2O_2 addition, TiO_2 phase composition and recycled TiO_2 on the photocatalytic degradation of methyl orange (MeO) in TiO_2 suspensions under ultraviolet (UV) illumination were primarily investigated. The results indicate that a low pH value, proper amount of H_2O_2 and pure anatase TiO_2 will facilitate the photocatalytic oxidation of the MeO solution. The photodegradation degree decreases with increasing the pH value of the solution and varies with different amounts of H_2O_2. Pure anatase TiO_2 shows better photocatalytic activity for MeO decolonization than biphase TiO_2. The photocatalytic mechanism of the as-synthesized TiO_2 nanoparticles was discussed.