An environmental assurance system by catalytic ultrasonic irradiation with functional TiO2 particles.

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The results of this study are summarized as follows:1. The presence of TiO_2 accelerates the formation of OH raidicals during ultrasonic irradiation even in the absence of UV irradiation. The effect of TiO_2 may be due to the heterogeneous nucleation of bubbles, which enhances the cavitation power. The effect of dissolved gases on the formation of OH radicals was further studied and the power of the dissolved gases on the formation of OH radicals was in the order Xe>Ar>O_2>N_2. The degassing of the irradiation solution completely suppressed the formation of OH radicals. These results indicate that the presence of TiO_2 accelerates the formation of OH raidicals during ultrasonic irradiation even in the absence of UV irradiation and the process may be mediated through the induction of cavitation bubbles in irradiating solutions.2. Ultrasonification of bisphenol A (BPA) and pentachlorophenol (PCP), a representative endocrine disruptors, were carried out in the presence of TiO_2 and the change in the concentration of BPA and PCP were measured by HPLC/ECD. The initial concentration of BPA (1 ppm) was gradually decreased with the irradiation time and was totally decomposed by 15 minute irradiation of ultrasound. The similar results were observed for PCP.3. It was shown that the rate of disinfection obtained in the case of TiO_2 was higher than that observed in the presence of Al_2O_3, indicating a higher synergistic effect for TiO_2. The results obtained in the disinfection of E. call showed that the addition of glutathione and histidine could suppress the cell disinfection process. These results were supported by the same results obtained in the disinfection of Legionella, indicating the primary role of hydroxyl radicals in this process.The irradiation of ultrasound on TiO_2 in aqueous solution significantly generate hydroxyl radicals which is responsible for the decomposition of the hazardous materials such as endocrine disruptors and pathogenic microorganisms.