Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

In this paper, micelle formation of a well known anionic surfactant, sodium dodecyl sulfate (SDS) in aqueous solutions of four structurally different sugars viz. ribose, glucose, sucrose and raffinose at wide temperature range T = (293.15-318.15) K has been studied. From specific conductance data, the value of CMC and XCMC have been calculated whose dependence on sugar concentration correlates well with the hydrophobic nature of sugar molecule. A non!Vlinear trend in CMC values is attributed to the presence of both hydrophilic and hydrophobic dehydrations. From XCMC values, thermodynamic parameters such as standard enthalpy ( deltaHm ), standard entropy ( deltaSm ), and standard free energy of micellization ( deltaGm ) have also been evaluated. The results of these thermodynamic parameters have been discussed in terms of the structural consequences of the intermolecular interactions. Enthalpy-entropy compensation gave linear dependence, thus suggesting that micellization of SDS is governed by the delicate balance of sugar-water interactions by changing the structural property of water in the presence of sugars. The effect of organic solvents such as dimethyl sufoxide (DMSO), methanol (MeOH) and dioxane has also been discussed in detail.