Abstract

Mixed crystal TiO2 nanoparticles were prepared from a precursor of TiO2 by hydrothermal-steam method. The effects of the reaction temperature and the reaction time on the photocatalytic activity of the brookite TiO2 were studied. The TiO2 samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Photocatalytic degradation of organic dye sulforhodamine B (SRB) under UV light (lambda < or = 387 nm) was used as probe reaction to evaluate the properties of the TiO2. The result showed that TiO2 prepared under 150 degrees C for 24 h had high photocatalytic activity. The size of the mixed crystal TiO2 was 14.20 nm. Brookite and anatase phase of the mixed crystal TiO2 were 63.6% and 36.4%, respectively. The dye discoloration and degradation rates were tracked, and the intermediate products hydrogen peroxide (H2O2) and hydrogen radicals (*OH) were determined during the photocatalytic experiments. The results indicated that photocatalytic degradation of brookite TiO2 mainly referred to the *OH radical mechanism. After 5 h, the mineralization and oxidation rates of SRB and 2,4-DCP mineralization were 89% and 78%, respectively. The catalyst showed good stability with no significant changes in catalytic properties after 5 cycles of SRB photocatalytic degradation experiments.