Interfacial and thermodynamic properties of anionic-nonionic mixed surfactant system: Influence of hydrophobic chain length of the nonionic surfactant

The influence of hydrophobic chain length in nonionic surfactants on interfacial and thermodynamics properties of a binary anionic-nonionic mixed surfactant was investigated. In this study, nonionic surfactants lauric-monoethanolamide (C(12)MEA) and myrisitic-monoethanolamide (C(14)MEA) were mixed with an anionic surfactant, alpha-olefin sulfonate (AOS). The critical micelle concentration (cmc), maximum surface excess (Gamma(max)), and minimum area per molecule (A(min)) were obtained from surface tension isotherms at various temperatures. The thermodynamic parameters of micellization and adsorption were also computed. Micellar aggregation number (N-agg), micropolarity, and binding constant (K-sv) of pure and mixed surfactant system was calculated by fluorescence measurements. Rubingh's method was applied to calculate interaction parameters for the mixed surfactant systems.