The surface organic modification of TiO2 particles with titanate coupling reagent,which was pre-coated with double layers of SiO2 and Al2O3,was studied.Experiments showed that the modified particles exhibited hydrophobic characteristics.The modification state of the particle surface was characterized by IR spectroscopic measurement,pyrolytic gas chromatography,thermogravimetric analysis and X-ray photoelectron spectra.The titanate coupling reagent binding with the hydroxyl on the particle surface was analyzed.The surface characteristics of pre-modification and post-modification particles were compared.
The inherent characteristics in the rapid expansion process of supercritical fluid solution were analyzed. The temperature change resulted from the throttling expansion of the supercritical fluid, and the strong turbulence in the expansion flow resulted from the quick change of the fluid pressure were experimentally measured. It was proposed that the temperature and turbulence in the expansion flow affect the particle nucleation, growth or coating process significantly.
Wang Tingjie, Sun Xiaoyu and JinYong (Department of Chemical Engineering, Tsinghua University Beijing, 100084,China)
