P11 マイクロバブル凝集挙動におよぼす超音波照射条件の影響

抄録

Microbubble with a diameter less than 50 urn in a liquid has very useful characteristics. However, it is difficult to control the dynamic behavior of microbubbles in a liquid. In our previous study, when the ultrasound is irradiated into the microbubble suspension that looks milky white, the suspension rapidly becomes clear. In this study, the mechanism of this behavior was investigated by visualization. Especially, the effects of surfactant addition, pH of solution and ultrasonic frequency on dynamic behavior of microbubbles in an ultrasonic field were investigated. Before ultrasonic irradiation, microbubbles stably dispersed in the liquid by electrical repulsion. After ultrasonic irradiation, microbubbles approached and were agglomerated by second Bjerknes force, and rise velocity of bubble was increased. After ultrasonic irradiation was stopped, the bubble dispersed again. This behavior of microbubble was able to be reversibly controlled by ultrasonic power. And, the size and shape of agglomerated bubbles were influenced by ultrasonic frequency. On the other hand, electrical repulsive force of microbubble decreased with lowering pH of solution, and microbubbles were coalesced at pH = 3.5. Then, the relationship between second Bjerknes force and potential of surface of the microbubble influence the agglomeration behavior.