(543g) Investigation of Dynamic Surface Tension Induced By Gas-Liquid Absorption in a Microfluidic Device

Surface tension plays an important role in gas-liquid dual-phase microflow. In the presence of interface active agents, dynamic surface tension rather than static surface tension dominates the emulsification process, including the droplet diameter, the size distribution, and so forth. However, the conventional measurement methods are no longer available to determine the dynamic surface tension in microflow system because of its extremely small scale. In this study, the dynamic surface tension induced by mass transfer was determined in situ in a microfluidic device. The instantaneous surface tensions at the bubble rupturing moment in a CO₂ absorption process were determined from the bubble diameter, according to the force balance at bubble breakup. The mass transfer across the interface caused up to a 7.2 mN/m reduction in the surface tension compared with the static surface tension. The decrease in the surface tension can be expressed into a Langmuir-Szyszkowski equation related to the CO₂ interfacial concentration. Our study provided an insight to the effect of mass transfer on multiphase fluid dynamics, which might be beneficial to the better design and control of microfluidic devices.