Computer simulation of chemical reactions occurring in collapsing acoustical bubble: dependence of free radicals production on operational conditions

Acoustic cavitation is responsible for both sonochemistry and sonoluminescence. In this theoretical investigation, computer simulation of chemical reactions occurring in an isolated cavitation bubble oscillating in water irradiated by an ultrasonic wave has been performed for various acoustic amplitudes, different static pressures and diverse liquid temperatures to study the relationship between these three key parameters in sonochemistry and the oxidants created in the bubble. The results of the numerical simulations indicated that the main oxidants created in an O-2 bubble are (OH)-O-aEuro cent radical and O atom. The amount of the oxidants formed in the bubble at the end of the bubble collapse increases as the acoustic amplitude increases from 1.5 to 3 atm. For each acoustic amplitude, there exists an optimal static pressure for the production of the oxidants, which shifts toward a higher value as the acoustic amplitude increases. Correspondingly, for each acoustic amplitude, an optimum of liquid temperature was observed at 20 A degrees C for (OH)-O-aEuro cent, HO2 (aEuro cent) and H2O2. The simple model adopted in this work, after comparisons with the trends obtained with the literature experimental observations, seems to satisfactorily explain the experimental observations and should practically aid in optimization of operating conditions for sonochemical reactions. Results from this study were discussed and some recommendations were given.