Synthesis of titania particles by low-temperature hydrolysis reaction of titanium alkoxide and their surface properties

Abstract

The titania particles were prepared by aging the mixture of titanium isopropoxide (TIP) and H2O at 318 K. The anatase titania particles were obtained by the aging procedure at 318 K for more than 16 h. The aging temperature was quite low to obtain anatase-type titania particles. According to the DTA measurement, the amount of amorphous phase included in the titania particles decreased with increases in the aging time. Furthermore, the titania particles obtained by aging the mixture of TIP and H2O at 318 K for 24 h contained no amorphous phase. The obtained titania particles had a high BET specific surface area of more than 250 m2/g. To characterize the titania surface, the adsorption isotherms of the organic dye molecules in an aqueous solution were measured. The negatively charged Evans blue molecules strongly adsorbed on the titania surface obtained by the low-temperature hydrolysis reaction as compared with the results of the methylene blue molecules. Furthermore, the decomposition kinetics of the dye molecules by the photocatalytic activity also deepened with the charge of the dye molecules. The relation between the UV irradiation time and the molar ratio of the decomposed dye molecules followed the Avrami equation. According to the results of the analysis using the Avrami equation, the Evans blue molecules were decomposed on the titania particle surface. In contrast, the methylene blue molecules were decomposed in the aqueous solution. The difference in kinetics was related to the interaction of the dye molecules and the titania surface. The high surface area of the titania particles obtained the low-temperature hydrolysis reaction of titanium alkoxides enhanced the effect of the surface interaction on kinetics of the photocatalytic activity.