STEADY-STATE INTERFACIAL-TENSIONS DURING DIFFUSION OF ORGANIC-ACIDS FROM HEXANE TO AQUEOUS ALKALINE-SOLUTIONS

Fatty acid molecules, when transported from a hydrocarbon phase toward an aqueous phase containing alkali, are ionized, followed by an expansion at the interface. This expansion, treated as a first-order chemical reaction, is a slow process and responsible for the pronounced transient interfacial tensions. As a function of time the transient interfacial tensions pass through a minimum before a steady state is reached. This steady state value is treated theoretically and compared with experimental data. Rather good agreement between theory and experiment is achieved. This system can be considered an example for interfacial resistance during mass transfer, but the known theory for interfacial resistance is too crude to describe the physicochemical behavior. © 1990.