Preparation of nano-TiO2 microspheres with high efficiency in photocatalytic degradation of gaseous benzene

The nano-TiO2 microspheres were prepared by a hydrothermal method with urea in ethanol/water solution in the presence of sodium sulfate. The prepared samples were characterized by X-ray diffraction, transmission electron microscopy, N-2 adsorption-desorption and UV-Vis diffuse reflectance spectroscopy, the effects of hydrothermal temperature on the nano-TiO2 microspheres morphology were investigated, and the photocatalytic activities toward gaseous benzene of the samples were studied. The results indicate that the microspheres are composed of tiny nanoparticles, the TiO2 microspheres pose high specific surface areas and uniform porous nanostructures, the optical absorption edges of the samples have "blue shift". The photocatalytic results confirm the benzene-degrading effectiveness of the TiO2 microspheres, especially, the results show that no benzene detected after 20 min reaction with TiO2 microspheres prepared at 180 degrees C, however, the produced CO2 concentration continues to increase, it indicates that TiO2 microspheres with very high adsorptive capacity can enhance the subsequent photocatalytic reaction, and the mineralization ratio of this TiO2 microspheres can be as high as 5. 5, which is double of P25 (2. 7).