Preparation Of Rare Earth Modified TiO₂ Areagels And Its Photocatalytic Performance

Photocatalytic technology has a wide application in the field of environmental protection.Especially the treatment of organic pollutants in wastewater, it will be able to mineralize and degradate completely the organic pollutants into CO2 and H2 O. TiO2 has many advantages as a semiconductor photocatalyst, and it has been widely used in this field. But the photocatalytic activity of TiO2 is not high, it usually needs to be modified. It is transparent or semitransparent solid, the light permeability of it is strong, these make the TiO2 release hole and electron. On the other hand, the particles of TiO2 aerogels are very small, in the range of quantum size, which makes the compoud of electron and hole to be not easy, and to improve the photocatalytic activity. Therefore, TiO2 aerogels become the advantaged light catalyst materials.Abased on all of above, the but Gd doping can make the light absorption bands of TiO2 shift to the visible light region, increase the activity of TiO2 in the visible light excitation. This experiment prepared Gd-doped porous TiO2 aerogels with ionic liquid by sol gel method, and completed the following researches:(1) By sol-gel method, using ionic liquid, and using the butyl titanate as titanium source,the TiO2 aerogels were aged under low temperature and normal pressure, so the mesoporous scale porous TiO2 aerogels were prepared. Through the characterization and photocatalytic properties test of the samples, it shows that the TiO2 aerogels prepared with the help of C6 mimBr was anatase and has large specific surface area, it can reach to 287.19 m2/g, most probable aperture was about 5.27 nm, and the pore size distribution was concentrated on the scale of mesoporous;the degradation rate of reactive brilliant blue KN-R is high, it can reach to 81.31%, the performance is better than P25.(2) Using the Gd(NO3)3·6H2O as the Gd source, the TiO2 aerogels are modified by further doping, and it broads its spectral range. By consideration of the doping amount of rare earth Gd, the concentration of ionic liquid, the temperature of aging process, aging time, pH value of solution and so on. The best conditions of preparation of the samples show that thedoping molar ratio is 1.5%, the concentration of ionic liquid aging solution is 3 mol/L, the aging temperature is 60 ℃, the aging time is 3 day and the concentration of aging solution is pH=5. The TiO2 aerogels prepared with the optimal conditions were anatase and own higher crystallinity, particle size of it is about 6 nm; the pore structures of vermicular or spongy are rich, aperture is mainly focused on 5 nm, the specific surface area is up to nearly 300 m2/g;the ability of photocatalytic degradation of reactive brilliant blue KN-R is obviously enhanced,it can be up to more than 90%, it is far more than P25.(3)Therefore different rare earth are doped based on experimental conditions, and contrast the photocatalytic activity. Light rare earth doping Ce makes its photocatalytic performance better than the Gd and Ho doped TiO2 aerogels.