Adsorption and Micellar Properties of Binary Ionic/Nonionic Surfactant Mixtures in Ethylene Glycol plus Water

The adsorption behavior and micellar properties of the mixed binary ionic/nonionic Surfactants containing cetyltrimethylammonium bromide (CTAB) and p-(1,1,3,3-tetramethylbutyl)polyoxyethylene Triton X-100 (TX-100) in aqueous mixture of ethylene glycol (EG) have been studied through surface tension and conductometry techniques. The Gibbs energy of the mixed micellization (Delta G(mic)degrees) was obtained from the critical micelle concentration (CMC) and counterion degree dissociation (alpha(diss)) values. The differences in the Gibbs energies of mixed micellization of TX-100/CTAB between water and water + EG mixtures were calculated to monitor the influence of cosolvent oil the micellization process. The role of the structure-breaking ability of EG (g(sb)) and electrostatic interaction in the process of micellization are surveyed in this article. The cosolvent effect on the interaction between two Surfactants, CTAB and TX-100, in a mixed monolayer at the air-liquid interface (beta(delta)) and mixed micelle (beta(M)) was analyzed oil the basis of regular solution theory. Furthermore, considering nonrandom mixing and headgroup size effects oil the basis of the Gibbs-Duhem relation, proposed by Hall, beta(M) was calculated. It was observed that, as the amount of EG ill the aqueous medium increased, the intermolecular interactions decreased for both the planar air/aqueous interface and the micellar systems. However, at higher volume fractions of EG, beta(M) increased because of reduction ill electrostatic self-repulsion interaction between ionic headgroups through mixing. Finally, the analysis of the variations of surface tension as a function of solution composition and total Surfactant concentration suggests that the surface activity of CTAB or TX-100 and their mixtures decreases with the increase in the amount of EG in aqueous media.