抄録
Hydroxyl (OH) radicals are produced by many methods such as ultrasound (US) irradiation and ultraviolet (UV) irradiation in the presence of photocatalyst. The OH radicals are reactive species and can oxidize hazardous organic substances into non-hazardous ones such as carbon dioxide and low molecular substances. In addition, ultrasonic irradiation of liquid causes atomization at the surface of the liquid bulk. In this work, we investigated the synergistic effect of US irradiation and UV irradiation on chemical oxidation rate using TiO_2 photocatalyst. The oxidation reaction of KI in aqueous solution was used to evaluate the effect. Results demonstrated that the rate constant of KI oxidation by simultaneous treatment of US/UV was higher than the sum of respective rate constants obtained by only US treatment and only UV treatment. Especially, when ultrasonic mists as well as solution bulk under ultrasonication were irradiated with UV, the oxidation reaction was significantly promoted. These results may suggest that efficient photocatalytic reactions are achieved via the production of ultrasonic mists not only containing photocatalyst particles but also having a higher specific surface area which are probably more favorable for effective irradiation with UV.
