Mass-Transfer-Controlled Dynamic Interfacial Tension in Microfluidic Emulsification Processes
Mass-Transfer-Controlled Dynamic Interfacial Tension in Microfluidic Emulsification Processes
复制标题
微流体乳化过程中传质控制的动态界面张力
DOI：
10.1021/acs.langmuir.6b00271
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发表时间：
2016
期刊：
影响因子：
3.9
通讯作者：
Luo Guangsheng
中科院分区：
文献类型：
--
作者：
Wang Kai;Zhang Liming;Zhang Wanlu;Luo Guangsheng
实验研究了滴滴表面表面活性剂不饱和吸附引起的界面张力变化。表面活性剂的传质和吸附以及新鲜界面的产生被认为是决定表面活性剂在液滴表面吸附率的主要因素。首先通过比较吸附深度和质量通量边界层厚度来区分表面活性剂的扩散和对流传质。然后通过引入有效扩散系数来计算特征传质时间。此外，通过将液滴生成时间除以特征传质时间t/tm来定义时间比，以便比较表面活性剂传质和液滴生成的速率。基于t/tm范围分析了不同表面活性剂的不同控制机制，并最终提出了使用简化的特征传质时间tm*的标准时间比来预测动态界面张力的出现。
Varied interfacial tension caused by the unsaturated adsorption of surfactants on dripping droplet surfaces is experimentally studied. The mass transfer and adsorption of surfactants, as well as the generation of fresh interfaces, are considered the main factors dominating the surfactant adsorption ratio on droplet surfaces. The diffusion and convective mass transfer of the surfactants are first distinguished by comparing the adsorption depth and the mass flux boundary layer thickness. A characterized mass transfer time is then calculated by introducing an effective diffusion coefficient. A time ratio is furthermore defined by dividing the droplet generation time by the characteristic mass transfer time,t/tm, in order to compare the rates of surfactant mass transfer and droplet generation. Different control mechanisms for different surfactants are analyzed based on the range oft/tm, and a criterion time ratio using a simplified characteristic mass transfer time,tm*, is finally proposed for predicting the appearance of dynamic interfacial tension.