In-situ coating process and disperse property studies of nanometer titanium dioxide prepared by hydrothermal synthesis

Nanometer titanium dioxide powders were prepared by hydrothermal precipitating method, and was modified by in-situ and formed-powder coating techniques with self-prepared 1100 disperser to investigate the disperse property of system obtained. Crystal phase and grain size of the modified powders were studied by XRD and TEM. The stability of the dispersed aqueous of modified TiO₂ nanopowders was measured by spectro-photometer with different amount of 1100 disperser and different pH values. Furthermore, the composite film of TiO₂ nanopowders was prepared. Results indicated that nanometer titanium dioxide, modified by in-situ process, comprised pure anatase phase with highly disperse degree and with the size at about 20 nm. The highest disperse stability was obtained with 1100 disperser of 8.0% by weight and when pH at 3 or 10. The formed-coating powders comprised anatase phase (73%) and rutile phase (27%) with apparently accumulated state. The in-situ modified TiO₂exhibited well-dispersed state in composite film and highly catalytic activity even at sunlight wavelength. The bactericidal detection results showed that, after 24 h exposure of composite film in natural sunlight, 99.8% of colibacillus could be killed.