Abstract
Experimental results have been obtained for mass transfer across liquid-liquid interfaces, utilising a novel Twyman-Green type interferometer and a flowing junction cell. Section One of the thesis is mainly concerned with mass transfer across plane interfaces. The system water-acetic acid-carbon tetrachloride was studied. Two cases were considered depending on the direction of transfer of the solute. In the first case acetic acid transferred from the water phase to the acid free carbon tetrachloride phase. Three initial concentrations of acetic acid in the water phase were used. The recorded interfacial concentrations showed that equilibrium was not established instantaneously. The growth rate of the interfacial concentration was comparatively slow, and was dependent on the initial strength of solute in the concentrated phase. The total amount of mass transfer (Mt) has been obtained as a function of exposure time and compared with the values of (Mt) calculated from theoretical equations. An empirical equation was developed to express the relationship between Mt and the exposure time (t). Having established the presence of an inter, facial resistance to mass transfer, it was found that the resistance was also time dependent. An empirical equation was developed to express the relationship between the interfacial resistance and exposure time. A modified pendant drop method was used to determine the interfacial tension of water-carbon tetrachloride interface for different solute (acetic acid) concentrations. The relationship between interfacial tension and interfacial resistance was established. An important aspect of the present work is that we were able to study the mass transfer process at very short time intervals from its inception. In the second case acetic acid transferred from the carbon tetrachloride phase to acid free water phase. Convective disturbances occurred in the carbon tetrachloride phase. This part of the work demonstrates the importance of the density changes accompanying the change in interfacial concentration. Section Two of the thesis deals with mass transfer to and from stagnant liquid drops. The total mass transfer (Mt), interfacial concentrations and concentration profiles have been obtained as a function of exposure time (t). Using this highly sensitive apparatus it is shown that at low concentrations (3 gm/lit) no eruptions in the drop surface could be detected while the diffusion occurred. At higher concentrations (30 gm/lit) eruptions developed almost instantaneously. This indicates the presence of a critical concentration of acetic acid at which interfacial eruptions occur.