Title: A continuum thermodynamic model of the influence of non-ionic surfactant on mass transfer from gas bubbles Show Chinese title

Title: 非离子表面活性剂对气泡传质的连续热力学模型

Abstract: Mass transfer of gaseous components from rising bubbles to the ambient liquid depends not only on the chemical potential difference of the transfer component but also on the interfacial free energy and composition. The latter is strongly affected by surface active agents that are present in many applications. Surfactants lead to local changes in the interfacial tension, which influence the mass transfer rates in two different ways. On the one hand, inhomogeneous interfacial tension leads to Marangoni stress, which can strongly change the local hydrodynamics. One the other hand, the coverage by surfactant molecules results in a mass transfer resistance. This hindrance effect is not included in current continuum physical models. The present work provides the experimental validation of a recently introduced extended sharp-interface model for two-phase flows with mass transfer that also accounts for the mass transfer hindrance due to adsorbed surfactant. The crucial feature is to account for area-specific concentrations not only of adsorbed constituents but also of transfer species, and to model mass transfer as a series of two bi-directional sorption-type bulk-interface exchange processes. The resulting model is shown to quantitatively describe experimental measurements on mass transfer reduction for the dissolution of CO$_2$ bubbles in different surfactant solutions. Show Chinese abstract

Abstract: 气体组分从上升气泡向周围液体的传质不仅依赖于传质组分的化学势差，还依赖于界面自由能和组成。后者受到许多应用中存在的表面活性剂的强烈影响。表面活性剂导致界面张力的局部变化，这以两种不同的方式影响传质速率。一方面，不均匀的界面张力导致Marangoni应力，这可以强烈改变局部流体力学。另一方面，表面活性剂分子的覆盖导致传质阻力。这种阻碍效应目前连续物理模型中未被包括。本工作提供了最近引入的扩展尖锐界面模型的实验验证，该模型用于考虑由于吸附表面活性剂引起的传质阻碍的两相流动中的传质。关键特征是不仅要考虑吸附组分而且要考虑传质物种的面积特异性浓度，并将传质建模为一系列双向吸收类型的体-界面交换过程。所得到的模型显示能够定量描述CO$_2$气泡在不同表面活性剂溶液中溶解的传质减少的实验测量结果。