Titania Coating of Wasted Silica Particles and their Photocatalytic Property

TiO2-coated SiO2 particles were prepared using industrially-wasted amorphous SiO2 powder by an alkoxide method, in which the mean particle size of SiO2 was approximately 100 nm. The SiO2 powder and titanium tetraisopropoxide were mixed in ethanol and an appropriate amount of distilled water was added to the suspension for hydrolysis of the alkoxide. The product was calcined in the temperature range from 600 to 1300°C to crystallize the deposited TiO2. The homogeneous deposition of TiO2 on the SiO2 surface was observed by SEM. It was found that the SiO2-support tended to retard the transformation from anatese to rutile. The maximum photocatalytic activity for decomposition of methyleneblue was obtained on the TiO2-coated SiO2 powder calcined at 1000°C, and was higher than that of a commercial TiO2 powder.