Thermodynamic studies on water-β-cyclodextrin-surfactant ternary systems

Conductance measurements are reported for double chain surfactants like N,N,N-octylpentyldimethylammonium (OPAC) and N,N,N-octyloctyldimethylammonium chlorides (OOAC) in water-β-cyclodextrin solution. From the specific conductivity data, the apparent critical micelle concentration (cmc∗) and the degree of counterion dissociation (β) were obtained at a fixed β-CD concentration (mβCD = 0.01190 mol kg−1, besides from the cmc∗ value and that in water (cmc) the stoichiometry of the surfactant-β-CD complex was calculated. Densities, heat capacities, enthalpies of dilution at 298 K and osmotic coefficients at 310 K were measured for the same systems; the apparent molar volumes, Vλ, and heat capacities, Cλ, of two surfactants in β-CD solution, calculated as functions of surfactant concentrations ms, have made possible to obtain the properties of transfer of the surfactant from water to β-CD-water solutions.