抄録
Introduction Sol-gel derived anatase phased TiO_2 powder was prepared by hydrolysis of titanium tetraisopropoxide (TTIP) developed under ultrasonic irradiation having different frequency. The ultrasound (US) influenced on the particles size of TiO_2 powder and the effect of US on the formation of fine particles was controlled by using reflection technique, in which the semi-cylindrical reflection plate was placed onto the vicinity of reaction vessel to make fine TiO_2 powder. We also examined photo-decomposition of rhodamine dye by the resultant TiO_2 under light irradiation. Experimental TiO_2 powder was synthesized by the hydrolysis of (0.125 mol) ITIP in the presence of 10% ethanol-water mixed solution under different frequency ultrasounds (28, 45, 100 kHz with 300 W/cm^2) for 1h at room temperature. The sol sample was aged to complete hydrolysis reaction for overnight. The precipitated TiO_2 particles were separated by centrifugation (3000 rpm) and dried at 100℃ for 8h. Dried sample was grinded and sintered at 300℃ for 1h. Characterization was accomplished by particle size distribution and Fourier transform infrared (FT-IR) spectroscope. The properties of US associated sol-gel derived TiO_2 powder was evaluated by photocatalytic decomposition activity to 10μM rhodamine dye. Results and discussion We found that the resultant sol-gel derived TiO_2 particles size was depended on the US intensity. The average TiO_2 particle size prepared in the absence of US was 52μm and 16, 28 and 50μm for TiO_2 particle prepared under 28, 45 and 100 kHz of US irradiation, respectively. For the preparation of TiO_2 particle under reflected US, the observed particle size was 11, 18 and 27μm as respective frequency 28, 45 and 100 kHz. It was examined that US frequency can controlled the particle size of resultant TiO_2 particle and US reflection technique is distinctly influenced at 100 kHz. Photocatalytic activity was determined by degradation of 10μM rhodamine percolate solution under UV irradiation. Changes of rohdamine percolate concentration were traced with decline of the absorption peak at 576 nm. The resultant absorbance data showed that the decomposition rate of the rhodamine dye was low with the sample prepared in the absence of US irradiation. It was known that the TiO_2 powder prepared under 28 kHz US had higher decomposition rate than those of 45 and 100 US. Further, it was presented that the reflection US technique was also affected to the decomposition of rhodamine percolate.
