Preparation Of Mesoporous Titanium Dioxide Photocatalyst And Its Application In Waste Water Treatment

It is widely known that waste water and gases are dangerous to environment and human beings. Photocatalysis is generally thought of as the catalysis of a photochemical reaction at a solid surface, usually a semiconductor. Titanium dioxide (TiO2) is usually used as a photocatalyst in treating hazardous materials.Hydrothermal method was used to prepare mesoporous TiO2 and Ce-doped TiO2 without using orgnic templates. TiO2 was charactered by X-ray powder diffraction (XRD), specific surface area (BET), scanning electron microscopy (SEM), UV-vis diffuse reflection absorption spectrum(UV-vis). Photoactivity was tested by decomposing methyl orange under UV-light.The influencing factors including ratio of tetra-n-butyl titanate (TNBT), water, ethanol, urea, ammonium sulfate, acetylacetone and hydrothermal time, hydrothermal temperature, calcination temperature for preparing TiO2 were reviewed. The specific area of prepared TiO2 reached as high as 325 m2/g and 190 m2/g after being calcinated at 450℃. The as-prepared sample shows type IV-like isotherm with an inflection of nitrogen adsorbed volume at p/po= 0.5 (type H2 hysteresis loop), indicating the presence of well-developed mesoporosity. The pore diameter is between 6 nm and 11 nm according to the prepared conditions.Hydrolysis of TNBT is the key factor to the photoactivity of TiO2. Proper ratio of TNBT, H2O and EtOH leads to the best photoactivity. The final appearance of TiO2 was affacted by acetylacetone. The TiO2 particles were fine and the diameter was around 1.2μm from the SEM images when adding 2.0 mL of acetylcaetone. The specific area was influenced by urea and ammonium sulfate. TiO2 prepared by hydrothermal method is anatase-stabled even after been calcinated at 450℃. The wavelength of ray absorbed was slightly red-shifted prepared with Degussa P25 (a common used commercial photocatalyst) and the photoactivity of prepared TiO2 was 10% higher than P25.Ce-doped TiO2 was prepared by hydrothermal method with ammonium ceric nitrate as precursor. No ceria crystyal peaks were found in XRD patterns with the m(CeO2):m(TiO2)= 0-10%(wt%).CeO2 was prepared by hydrothermal and precipitation method. Cubic crystal structure was found from the XRD patterns.