Variations in the size distribution of bulk nanobubbles in response to static pressure increases

The present study examined the effects of increasing static pressure on the size distribution of nanobubbles (ultrafine bubbles). The total volume concentration of the nanobubbles decreased with increasing the static pressure while the average size remained relatively constant. This result indicates that many of the detected objects were gaseous nanobubbles. The behavior of these nanobubbles in response to sonication is discussed herein based on measurements of sonoluminescence intensity. At extremely high acoustic amplitudes, the observed intensity was greater in the presence of nanobubbles as compared to pure water. Accordingly, nanobubbles have the potential to provide nucleation sites for sonochemistry. (C) 2020 The Japan Society of Applied Physics