Micelle Formation of Aerosol-OT Surfactants in Sea Water Salinity

Abstract

Gemini surfactants group recently showed importance in screening techniques for the evaluation and selection of chemicals for enhanced oil recovery. Aerosol-OT (sodium bis (2-ethylhexyl) sulfosuccinate, AOT) is a versatile anionic Gemini surfactant which is widely used in the chemical and biophysical research, which is also included in the category of sulfonated hydrocarbons and shows high potential in laboratory experiments. In this paper, the micellar behaviour of anionic AOT in presence of high sodium salt concentration was studied at different temperature from (25–105)∘C. Surface tension techniques using duoy ring were applied for each surfactant concentration to find the critical micelle concentration (CMC) at each temperature. Several thermodynamic parameters were also reported as the standard Gibbs energies of micellization, Δ G0; the standard enthalpy change of micellization, Δ H0; and the standard entropies of micellization, Δ S0, were calculated from the temperature effect on the CMC. Results showed that CMC values increased with temperature. The enthalpy of micellization was found to be negative in all cases, and it showed a strong dependence on temperature in the AOT solution in the presence of high concentration of NaCl system.