Preparation and properties of stable nanocrystalline anatase TiO2 colloids

The nanocrystalline anatase TiO2 colloid has widely been applied in solar energy conversion, photo-degradation of organic pollutions, photochemical disinfection, processing of sensors, and papermaking. It can be obtained from the hydrolysis of titanyl organic compounds [TiO(OOCCH3)(2) and Ti2O(OC4H9)(2)(OOCCH3)(4)] at low temperature and normal pressure. TEM (Transmission Electron Microscope), SEM (Scattering Electron Microscope), and LS (Layer Scattering) analysis showed that the colloidal particles are spherical and possess a narrow size distribution, that the mean size (80 degrees C, 2 h, sample B) is 8.9 nm and its isoelectric point is 6.67. The S-BET of the gel powders are 262.7457 m(2)/g (60 degrees C, 2 h, sample A) and 258.0024 m(2)/g (80 degrees C, 2 h, sample B). Research experiments showed that the turbidities of colloidal solutions decreased along with the decrease of water content in the mixed water-alcohol dispersants, which predicated that the colloidal stability fell when lowering the electrical conductivity of the dispersant. The zeta potentials of the colloids are 14 mV similar to 30 mV at pH 4.5 similar to 6.0 in the presence of 0.5 . 10(-2) mol L-1 NaNO3 electrolyte. Furthermore, the UV absorbance of the nanocrystalline TiO2 colloidal solutions increased with a decrease in particle size. The experimental results of photocatalytic degradation of the dye rhodamine revealed that the nanocrystallinc TiO2 colloidal particles from this preparation method have good photocatalytic activity, which is better if doped with 0.2 % Fe3+.