STUDIES ON THE SURFACE AND THERMODYNAMIC PROPERTIES OF SOME SURFACTANTS IN AQUEOUS AND WATER+1,4-DIOXANE SOLUTIONS

From surface tension data surface properties, such as, surface excess concentration, minimum area per molecule, surface pressure at the c.m.c., as well as thermodynamic quantities of micellization and adsorption, have been determined for four different surfactants, viz., sodium dodecyl sulphate (SDS), sodium dodecylbenzene sulphonate (SDBS), dodecyltrimethylammonium bromide (DTAB) and Triton X-100. The measurements for each system has been carried out at 303.15 and 313.5 K in aqueous and water + 1,4-dioxane solutions. The results indicate that the micellization and adsorption at the liquid/air interface of these surfactants are governed, primarily, by the entropy gain rather than the energy effect. Whereas micellization of SDS is favoured in the presence of 1,4-dioxane, it is not favoured in the presence of DTAB and Triton X-100.