ARTICLE:

• A STUDY OF THE THERMODYNAMIC COUPLING OF MASS AND MOMENTUM TRANSPORT AT LIQUID/LIQUID-INTERFACES  download article

Alexander Tokarz
Institut für Verfahrenstechnik, Universitat Hannover, Callinstr. 36, 30167 Hannover, Germany

Dieter Mewes
University of Hannover, Institut fur Verfahrenstechnik (Process Engineering), Callinstr. 36, 30167 Hannover, Germany

ABSTRACT

Recent theoretical investigations on the thermodynamics of transport processes at interfaces conclude that there is a thermodynamic coupling between the stresses acting within the interfacial region and the mass transfer processes. Applying this theory to the transport of a component across an interface, it is deduced that there is an influence of the dilation of an interface on the mass transport. To experimentally verify this assumption, experiments are carried out in a flow cell where the plane interface between two immiscible liquids is dilated in a flow field. The flow field near the interface is measured non-intrusively using Laser-Doppler-Velocimetry (LDV). The mass transfer across the interface is measured by means of holographic interferometry. From these measurements, it is shown that Marangoni effects occur even for very low concentrations of the transfer component. The intensity of the effects is strongly dependent on the amount of surface active contaminants present at the interface. Despite the high accuracy of the optical measuring system, an effect of the dilational stress as a driving force for the mass transfer is not experimentally verified for the system being investigated. The reasons for that remain to be further illuminated.

 download article

« Previous article         Next article »