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In aqueous solution at 40 °C, the micellization behavior of the binary mixtures constituted by an amphoteric sodium n-dodecyl diamine sulfonate and a cationic octadecyltrimethyl ammonium bromide has been investigated by the tensiometric technology. The values of critical micelle concentration (cmc) were determined by surface tension measurement of aqueous solution. The experimental data were analyzed according to various mixing thermodynamic models within the framework of the pseudophase separation model. The values of mixed cmc have been predicted successfully by both the Rubingh’s and Rodenas’s treatments. Various parameters like the mixed cmc, interaction parameters between surfactants (β12), the compositions and activity coefficients in mixed micelles as well as thermodynamic properties have been determined using Lang, Rubingh, Rodenas, and Rosen approach. Over the entire composition range investigated, the mixed micelle formation, non-ideal or ideal mixing, and synergistic effect or antagonism are explained by the electrostatic interaction between ionic headgroups of surfactants and the steric effect of surfactant. Thermodynamic parameters favor the process of micellization which is found to be entropy-driven.

The micellization of binary mixtures of sodium dodecyl diamino sulfonate (C12AS) and nonionic octylphenol polyoxyethylene ether (10) (OP-10) was investigated in aqueous solution at a pH of about 6.0. Two techniques, UV–Vis spectroscopy using pyrene as a probe and surface tensiometry, were employed in this work to obtain information on the micellization behavior of the mixed C12AS/OP-10 system. The interaction parameters between the two components, activity coefficients in mixed micelles, compositions of mixed micelles, and thermodynamic parameters of micellization (calculated using Clint’s equation, Rubingh’s treatment based on regular solution theory, and Rodenas’s treatment considering the Gibbs–Duhem equation) were evaluated for this mixed surfactant system. The results show that the synergistic effect between C12AS and OP-10 in all mixed systems plays a vital role in the reduction of the overall critical micelle concentration (cmc) value in aqueous solution. In the process of micellization, both the steric effect of the head group and the charge density for C12AS affect the formation and stability of the mixed micelles, and the entry of a small amount of C12AS into the unconsolidated micelle of OP-10 is more favorable to the formation of the mixed micelle by promoting the reduction of the mixed micelle cmc value. Thermodynamic data show that micellization for the mixed C12AS/OP-10 system is both an enthalpy and entropy driven process.

A facile, efficient and substrate-selective oxidation of the primary amines with NaClO as oxidant catalyzed by β-cyclodextrin (β-CD) has been developed in water for the first time, and the behavior of β-cyclodextrin that catalyzed the primary amines to nitriles in water was investigated. It was found that the primary amines which could form host-guest complexes with β-cyclodextrin were oxidized to nitriles with excellent yields at ambient temperature. The results show that β-cyclodextrin worked not only as a solubilizing agent but also as a catalyst in these reactions.