Development of the fumed TiO2 having high content of rutile structure and dispesibility using the dry-type of surface modification and the thermal treatment

Abstract

The effect of dry-type surface modification of a fumed TiO2 and the thermal treatment were studied to synthesize the new fumed TiO2 having a high content of rutile structure and high dispersibility. The fumed TiO2 was modified with various metallic alkoxides to prepare precursors and next the resulted precursors were thermally-treated by the novel natural dropping method with a very short heating time, less than 1 s. The focus of this investigation was on the metallic alkoxide species as a surface modification agent and morphologies of both the precursor and thermally-treated fumed TiO2. The morphologies and nanostructures of the obtained fumed TiO2 were characterized. The carbon content and agglomerate of the precursor influenced on the transformation ratio from anatase to rutile structure. It was confirmed that the dry-type surface modification with tetraethoxysilane (TEOS) and titanium tetra-isopropoxide (TTIP) at room temperature is very effective method to prepare precursors for the next thermal treatment. The thermally-treated fumed TiO2 modified with TTIP showed 100% rutile structure with pure TiO2 composition at 1400 °C. The thermally-treated fumed TiO2 modified with small quantities of TEOS exhibited both 100% rutile structure and excellent dispersibility. This high dispersibility caused from a sponge-like structural characteristic of the agglomerate and static electricity repellence by coated SiO2 layer. The thermally-treated fumed TiO2 modified with TEOS and TTIP showed the color tone shift can be attributed to rutile structure. It was revealed that the combination of dry-type surface modification and natural dropping thermal treatment is an attractive method to prepare the new fumed TiO2 with 100% rutile structure maintaining the high dispersiblity.