Surface Modification of Sericite Using TiO2 Powders Prepared by Alkoxide Hydrolysis: Whiteness and SPF Indices of TiO2-Adsorbed Sericite

Titania (TiO₂) powders have been prepared from the 0.025-M titanium isopropoxide/ethanol solution and the 0.5-M distilled water/ethanol solution. The prepared TiO₂ powders showed an anatase phase and a rutile phase after heat treatment at 500°C for 2 h and 1000°C for 2 h, respectively. The heterocoagulation adsorption between TiO₂ powder and sericite surface in water was achieved in the range of pH 3.63.7 (where this pH range shows a maximum Zeta-potential difference for two powders). On the other hand, an anomalous transformation behavior appeared in the TiO₂-adsorbed sericite after heat treatment at 1000°C. The surface modification of sericite through the TiO₂-adsorption improved the whiteness as well as the SPF (Sun Protection Factor) indices.