Thermodynamics of solutions containing surfactant in mixed solvent

Abstract

Surface tension and specific conductance data have been measured to determine critical micelle concentration (CMC) values for DTAB and Triton X-100 in mixed solvent (water + α-, + β- and ϒ-picoline solutions) at 298.15, 308.15 and 318. 15K. The observed data have been utilized to evaluate surface parameters, i.e., maximum surface excess concentration (Г_max), minimum area per molecule (A_min) at air-liquid interface, the surface pressure at CMC (π_cmc) and standard thermodynamic parameters of micellization, adsorption and transfer of surfactant from aqueous to mixed solvent. The observed specific conductance data have been utilized to evaluate the counter-ion association constant (α) and limiting equivalent conductance (λ_o), using Onsager's relationship. The observed data have been interpreted in terms of intermolecular interactions operating between various components in solution.