P14 暗条件・超音波照射下における光触媒活性の発現に関する研究(ポスターセッション)

抄録

Recently, it has been reported that photocatalytic reaction drives using ultrasonic (US) irradiation even under dark condition. However, its mechanism does not become clear in detail. In this study, we evaluate the removal ratio of organic compounds in water phase based on photocatalytic activity with 50 kHz US irradiation under dark condition. In order to clarify the influences of TiO_2 crystal structure and the physical properties of target compounds, three crystal types of TiO_2 and two different aldehydes such benzaldehyde (C_6H_5CHO) and formaldehyde (HCHO) were used for degradation experiments. TiO_2 (P25) suspension with US irradiation under dark condition (US/P25) enhanced removal ratios of both aldehydes, from 8.2% (US only) to 17% (US/P25) in HCHO, and from 43% (US only) to 57% (US/P25) in C_6H_5CHO. On the other hand, the effect of crystal structure of TiO_2 was evaluated by comparing US/P25 with US/ST21. In the case of using TiO_2 including rutile type structure (P25), the removal ratio was slightly improved in C_6H_5CHO. Furthermore, US/ST21 was compared with US/ST01 from the viewpoint of the particle size. US/ST01 with smaller particle size enhanced removal ratio in C_6H_5CHO. In all experiments, no change of removal ratio was confirmed in HCHO indicating that TiO_2 crystal structure and the physical properties effect on removal ratio of hydrophobic compound. Thus, it was estimated that photocatalytic reaction by US/TiO_2 could be occurred in hydrophobic field near the cavitation bubble.