抄録
Computer simulations of bubble oscillations in liquid water irradiated with ultrasound are performed under the experimental condition of single-bubble sonochemistry [1]. The model used in the present computer simulations are described in Refs. [2-6]. In the computer simulations, effect of non-equilibrium evaporation and condensation of water vapor at the bubble wall and that of chemical reactions of gases and vapor inside a bubble are taken into account. The calculated number of OH radicals dissolving into the surrounding liquid from the interior of the bubble agrees sufficiently with the experimental data. OH radicals created inside a bubble at the end of the bubble collapse gradually dissolve into the surrounding liquid during the contraction phase of an ultrasonic wave although one third of the total amount of OH radicals that dissolve into the liquid in one acoustic cycle dissolve in 0.1 μs at around the end of the collapse. The main oxidant which dissolves into the liquid is not OH radical but O atom which is created by the dissociation of oxygen molecules and water vapor molecules inside a collapsing bubble. It is suggested that the main oxidant in sonochemical reactions for a multibubble system in water in which oxygen is dissolved as in the case of air is not OH radical but O atom in contrast to the widely used assumption that OH radical is the main oxidant.
