Effect of electrolyte solutions on sunflower oil water interfacial tension in presence of surfactant

Abstract

The basic ingredients of cosmetics are usually an oil phase, water phase and a surfactant. Anionic surfactants are usually used in cosmetics as they have lower CMC values. But due to presence of an oily phase the surfactant used should have antifungal or antibacterial properties also. So CTAB was used as surfactant due to its antifungal properties and ability to withstand precipitation in presence of electrolytes. Interfacial tension is an important property for characterization of microemulsions. This report mainly focuses on the effect of inorganic electrolytes on interfacial tension in the sunflower oil/water system in the presence of a cationic surfactant. The objective of this study is to obtain insight into the effect of different electrolytes such as sodium chloride, calcium chloride, sodium phosphate and sodium sulphate on the surfactant adsorption characteristics. The experimental interfacial isotherms were fitted with Langmuir and Frumkin Adsorption models. The results indicate an increase in surfactant adsorption in presence of electrolytes. Also higher concentration of electrolyte increases the surfactant adsorption by screening electrostatic repulsions between surfactant head groups.