Zuo Yi Y, Li Dongqing, Acosta Edgar, Cox Peter N, Neumann A Wilhelm
Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON, M5S 3G8, Canada.
Langmuir. 2005 Jun 7;21(12):5446-52. doi: 10.1021/la050281u.
A new method combining axisymmetric drop shape analysis (ADSA) and a captive bubble (CB) is proposed to study the effect of surfactant on interfacial gas transfer. In this method, gas transfer from a static CB to the surrounding quiescent liquid is continuously recorded for a short period (i.e., 5 min). By photographical analysis, ADSA-CB is capable of yielding detailed information pertinent to the surface tension and geometry of the CB, e.g., bubble area, volume, curvature at the apex, and the contact radius and height of the bubble. A steady-state mass transfer model is established to evaluate the mass transfer coefficient on the basis of the output of ADSA-CB. In this way, we are able to develop a working prototype capable of simultaneously measuring dynamic surface tension and interfacial gas transfer. Other advantages of this method are that it allows for the study of very low surface tensions (<5 mJ/m2) and does not require equilibrium of gas transfer. Consequently, reproducible experimental results can be obtained in a relatively short time. As a demonstration, this method was used to study the effect of lung surfactant on oxygen transfer. It was found that the adsorbed lung surfactant film shows a retardation effect on oxygen transfer, similar to the behavior of a pure DPPC film. However, this retardation effect at low surface tensions is less than that of a pure DPPC film.
提出了一种将轴对称液滴形状分析（ADSA）和俘获气泡（CB）相结合的新方法，以研究表面活性剂对界面气体传递的影响。在该方法中，在短时间内（即5分钟）连续记录气体从静态俘获气泡向周围静止液体的传递。通过图像分析，ADSA-CB能够得出与俘获气泡的表面张力和几何形状相关的详细信息，例如气泡面积、体积、顶端曲率以及气泡的接触半径和高度。基于ADSA-CB的输出建立了稳态传质模型，以评估传质系数。通过这种方式，我们能够开发出一种能够同时测量动态表面张力和界面气体传递的工作原型。该方法的其他优点是它允许研究非常低的表面张力（<5 mJ/m²），并且不需要气体传递达到平衡。因此，可以在相对较短的时间内获得可重复的实验结果。作为示例，该方法用于研究肺表面活性剂对氧气传递的影响。结果发现，吸附的肺表面活性剂膜对氧气传递表现出阻滞作用，类似于纯二棕榈酰磷脂酰胆碱（DPPC）膜的行为。然而，在低表面张力下这种阻滞作用小于纯DPPC膜。
