SURFACTANT SURFACTANT INTERACTIONS IN THEIR BINARY-MIXTURES IN THE MIXED-SOLVENT 1,4-DIOXANE+H2O

Surface tension and viscosity measurements have been carried out for t wo surfactant binary mixtures, namely, sodium dodecyl sulphate (SDS)+T riton X-100 and dodecyltrimethylammonium bromide (DTAB)+Triton X-100, each in 1,4-dioxane+H2O at 303.15 and 313.15 K. From the mixed critica l micelle concentration (values obtained from surface tension data), t he interaction parameter beta has been calculated using the regular so lution treatment of Rubingh for mixed surfactant micelles; beta values have been rationalized in terms of the intermolecular interactions be tween unlike surfactant molecules in the mixed solvent. The magnitude of surfactant-surfactant interactions within the mixed micelles in 1,4 -dioxane+water is lower than that in pure water. Further, interaction between anionic-non-ionic surfactants was found to be stronger than in cationic-non-ionic surfactant.