Interfacial and Micellization Behavior of Cetyltrimethylammonium Bromide (CTAB) in Water and Methanol-Water Mixture at 298.15 to 323.15 K

The micellization behavior of cetyltrimethylammonium bromide (CTAB) in water, 0.1, 0.2, 0.3, and 0.4 volume fractions of methanol at 298.15, 308.15, 318.15, and 323.15K were investigated by surface tension measurements. The effect of methanol on values of critical micelle concentration (cmc), free energies of micellization (Delta G(m)(o)), and surface properties viz. maximum surface excess concentration (Gamma(max)), area occupied by per surfactant molecule (A(min)), surface pressure (pcmc), solution surface tension (pi(cmc)), solvent surface tension (gamma(o)), free energies of adsorption (Delta G(ads)(0)), the efficiency of adsorption (pC(20)), effective Gibbs free energy (Delta G(eff)(o)), and free energy of surface at equilibrium (Gmin) were investigated using surface tension values. Other parameters such as the packing parameter (P), aggregation number (N), concentration of surfactant in the bulk phase (C-20), relation between A(min) and p(cmc), and correlation of slopes (dc/d logC), gamma(o)/c(cmc), Gamma/Gamma(max), cmc/C-20, Delta G(ads)(o)/Delta G(m)(o), and cmc/pC(20) with the volume fraction of methanol are calculated and discussed in the light of the experiment done.