Abstract
The microbubble generator with a hollow ultrasonic horn is a recent development that can easily generate large quantities of microbubbles with a diameter of less than 100 μm. However, it still presents some drawbacks such as not being able to produce a sufficiently large gas flow rate for industrial applications, whereas the ultrasonic oscillation consumes large amounts of power. In this study, we developed a microbubble generator with an interchangeable orifice, and we evaluated the effect of the orifice shape on optimizing the microbubble generation through the time evolution of dissolved oxygen in oxygen-bubbled water, as well as the distribution of the bubble diameters. We also evaluated whether the generator has the sonochemical qualities required for practical applications by investigating the degree of degradation of indigo carmine. Our results revealed that a multi-orifice horn with orifices that were sufficiently apart to prevent the coalescence of the generated bubbles was well suited for microbubble generation and sonochemical reactions.
