Effect of Particle Addition on Ultrasonic Degradation Reaction Rate

Abstract

The ultrasonic degradation of methylene blue at a frequency of 490 kHz was carried out in the absence and presence of TiO2 or Al2O3 particle, and the effects of amounts of particle on the enhancement of degradation rate constant estimated by assuming first-order-kinetics were investigated. The degradation reaction was enhanced by particle addition, and the apparent degradation rate constant is proportional to the increase in amount of particle. In addition, the constant of proportionality is not influenced by degraded material and ultrasonic frequency. However, particle type influences the constant of proportionality, and the value of TiO2 particle is about 6 times as large as that of Al2O3 particle.

Comparison of Threshold Power between Methylene Blue Degradation and KI Oxidation Reaction Using Ultrasound

“…In our previous study, there is a relationship between SE KI value and degradation rate constant of methylene blue [14] [15] [16]. In addition, it has been reported that the ultrasonic degradation of methylene blue is enhanced by TiO 2 particle addition under dark condition [23] [24] [25], and the presence of TiO 2 particle accelerates the generation of hydroxyl radicals during ultrasonic irradiation even in the absence of UV irradi- ation [26]. Moreover, it has been also reported that the ultrasound and TiO 2 particle exhibit synergistic effects in the degradation of azo dye of acid orange 8, and the origin of the synergistic effect is considered to be the formation of additional hydroxyl radicals by TiO 2 particle from the extra hydrogen peroxide produced by ultrasound [27].…”