Detection and analysis of reactive oxygen species (ROS) generated by nano-sized TiO2 powder under ultrasonic irradiation and application in sonocatalytic degradation of organic dyes

Recently, the sonocatalytic technology using various semiconductors combined with ultrasonic irradiation has been received much attention to solve the environmental problems. In this paper, nano-sized titanium dioxide (TiO2) powder as a sonocatalyst was irradiated by ultrasound and the generation of reactive oxygen species (ROS) during sonocatalytic reaction process has been estimated by the method of Oxidation–Extraction Photometry (OEP). That is, the 1,5-diphenylcarbohydrazide (DPCI) can be oxidized by ROS into diphenylcarbonzone (DPCO), which can be extracted by the mixed solution of benzene and carbon tetrachloride and show the great absorbance at 563 nm wavelength. The synergistic effect of TiO2 and ultrasonic irradiation was estimated and some influencing factors, such as ultrasonic irradiation time and TiO2 addition amount on the generation of ROS were reviewed. The results indicate that the quantities of generated ROS increase with the increase of ultrasonic irradiation time and TiO2 addition amount. Moreover, the relationship between quantities of generated ROS and DPCI concentration was also studied. And then, several quenchers were used to determine the kind of the generated ROS. At last, the researches on the sonocatalytic degradation of organic dyes and the corresponding reaction kinetics have also been performed, which is found to follow the pseudo first-order kinetics approximately. This paper may offer some important subjects for broadening the applications of sonocatalytic technology.