ADSORPTION OF SHORT-CHAIN FATTY ACIDS AND THEIR IONS AT OIL/WATER INTERFACE

Interfacial tension of the oil/water system has been measured by the drop-volume method as a function of the aqueous concentration of a number of short-chain monocarboxylic acids and their sodium salts. The derived pressure-area data of the unionized acids have been found to obey, in general, Langmuir's equation of state for the mobile monolayer whereby the co-area (A0) per adsorbed molecule has been evaluated. The data have also been found to fit satisfactorily with the adsorption isotherm for the mobile monolayer at the liquid-liquid interface. The adsorption energies of the acids and their sodium salts calculated with the help of this isotherm have been compared. © 1968.