(671g) Dynamic Interfacial Tension during Droplet/Bubble Generation at Microchannel Junctions - an Important Mesoscale Scientific Issue in Multiphase Microflow Study

Authors: 
Wang, K. - Presenter, Tsinghua University
Riaud, A., Paris Sorbonne Cite Universite
Zhang, H., Tsinghua University
Luo, G., Tsinghua University
The dynamic interfacial tensions caused by surfactant adsorption and chemical reactions during droplet/bubble generation process at microchannel junctions are important mesoscale scientific issue between molecule and microchannel scales. This phenomenon exhibits the variations of interfacial composition during fluid particle generations with chemical processes, which is commonly taken place in microflow reaction and separations. This presentation gives a summary of our recent studies focusing on the determination of dynamic interfacial tension at during the droplet and bubble generations T-shaped1 and coflowing microchannel junctions2, and the variation laws of interfacial compositions with several surfactant absorption processes3 as well as the chemical reaction of CO2 and MDEA solution4. Experimental results show increase of decrease in interfacial tension from the static interfacial tension with equilibrium states. The Marangoni effect caused the gradient of dynamic interfacial tension is further exhibited by LBM simulations5, which is helpful for the understanding of multiphase microflow processes. Funding supports are from National Natural Science Foundation of China (21776150, 91334201, U1302271).

References:
1. Wang K, Lu YC, Xu JH, Luo GS. Determination of dynamic interfacial tension and its effect on droplet formation in the T-shaped microdispersion process. Langmuir. 2009; 25: 2153-2158.
2. Wang K, Xie LS, Lu YC, Luo GS. Generating microbubbles in a co-flowing microfluidic device. Chem Eng Sci. 2013; 100: 486-495.
2. Wang K, Zhang LM, Zhang WL, Luo GS. Mass-transfer-controlled dynamic interfacial tension in microfluidic emulsification processes. Langmuir. 2016; 32: 3174-3185.
4. Yang L, Liu G, Luo S, Wang K, Luo G. Investigation of dynamic surface tension in gas-liquid absorption using a microflow interfacial tensiometer. React Chem Eng. 2017; 2: 232-238.
5. Riaud A, Zhang H, Wang XY, Wang K, Luo GS. Numerical study of surfactant dynamics during emulsification in a T-junction microchannel. Langmuir. 2018; doi: 10.1021/acs.langmuir.8b00123.