抄録
It has been well-known that ultrasonic irradiation of air-saturated aqueous solution results in the decrease of pH which attributed to the formation of nitrite and nitrate. In the present study, effects of ultrasonic intensity on the rate of formation of nitrite and nitrate were investigated in detail. The rate of formation of nitrite and nitrate increased with increasing ultrasonic intensity up to 0.70W・cm^<-2>. However, it decreased at the higher intensity. On the other hand, the ratio of nitrate to nitrite increased monotonously as the intensity increased. This phenomenon is suggested to be strongly influenced by the nature of cavitation bubbles with high temperature and high pressure. Thus, the formation mechanism of nitrite and nitrate is proposed on the basis of the thermodynamics and kinetics taking into account the Zeldovich mechanism and aqueous sonochemistry.
