Abstract
Cationic surfactants of alkyl (dodecyl, tetradecyl and cetyl) trimethyl ammonium bromide (C(12)TAB, C(14)TAB and C(16)TAB) respectively can be used to study micellization phenomenon in water-acetonitrile mixtures. Their critical micelle concentrations are measured by using different techniques such as conductivity, UV spectra and density at different mole fractions of acetonitrile and temperatures. Effects of adding NaBr to C(12)TAB and C(14)TAB solutions are discussed from conductance technique. Thermodynamics of micellization are studied by applying equilibrium model at different X-AN and temperatures. Gibbs energies of transfer per methylene group (delta DG/delta n(c)) are calculated at 298 K but at different X-AN. The differences in partial molar volume (Delta V-sur) for those solutions below and above (critical micelle concentration) formed are estimated via density measurements and the related aggregation numbers can be calculated from Huisman's treatment and compared with Delta V-sur values. Finally, the Krafft phenomena for given solutions are derived and discussed.