Preparation of TiO₂ nanoparticles by supercritical carbon dioxide

Nano-sized titanium dioxide TiO₂ powder was successfully prepared from its precursor titanium (IV) isopropoxide (TTIP) by a system comprising of supercritical fluids microemulsion and supercritical-drying method, in which TTIP reacted in reversed micelles formed by surfactant Zonyl FSJ employing a supercritical carbon dioxide system. The milky white product, collected from the bottom of the pressure cell turned into sol-gel after sitting in the air for 5 days. Amorphous TiO₂ particles with particles size 2-7 nm can be obtained from the sol-gel by the supercritical-drying method. The amorphous TiO₂ particles were converted to anatase phase by calcining at 500 °C. Characterization of the TiO₂ powder consisted of TEM, XRD and EDS methods.