空気曝気水における発泡気泡の準静的成長

抄録

Microbubble aeration is used to dissolve gases into water and is an important technique in agriculture and industry. We can measure concentration of dissolved oxygen (DO) in aerated water by commercial DO meters. However, there do not exist commercially available techniques to measure concentration of dissolved nitrogen (DN). In the present study, we propose a method to measure DN in aerated water with the aid of EpsteinPlesset-type analysis ; particularly, we are interested in how the fractions of DN and DO are altered before and after aeration. Gas-supersturated water is produced by applying aeration with micron-sized air bubbles and is then stored in a glass container. The diffusion-driven growth of a bubble nucleated at the glass surface is recorded with a video camera. The bubble growth rate is compared to the extended Epstein-Plesset theory that models mass transfer of both DO and DN into the surface-attached bubble. Given the DO measurements, we infer the DN level from fitting between the experiment and the theory. The fitted DN level is found to exhibit a deviation from Henry's prediction.