THERMODYNAMICS OF SOLUTIONS CONTAINING SURFACTANT IN MIXED-SOLVENT

Surface tension and specific conductance data have been measured to de termine critical micelle concentration (CMC) values for DTAB and Trito n X-100 in mixed solvent (water + alpha-, + beta- and gamma-picoline s olutions) at 298.15, 308.15 and 318.15K. The observed data have been u tilized to evaluate surface parameters, i.e., maximum surface excess c oncentration (Gamma max), minimum area per molecule (A(min)) at air-li quid interface, the surface pressure at CMC (pi(cmc)) and standard the rmodynamic parameters of micellization, adsorption and transfer of sur factant from aqueous to mixed solvent. The observed specific conductan ce data have been utilized to evaluate the counter-ion association con stant (alpha) and limiting equivalent conductance (lambda(o)), using O nsager's relationship. The observed data have been interpreted in term s of intermolecular interactions operating between various components in solution.