Thermodynamic and solution properties of sodium valporate in aqueous solution and its interaction with cetyl trimethylammonium bromide (CTAB)

Abstract

This manuscript reports the volumetric, viscometric and aggregation properties of sodium valporate in aqueous solution. The interaction of drug with cationic surfactant (CTAB) was also studied. From volumetric study, partial molar volume, Hepler's constant, partial molar expansivity and isobaric thermal expansion coefficient were calculated while from viscometric study, the constants of Jones-Dole equation and thermodynamic parameters of viscous flow like free energy change, entropy change and enthalpy change were calculated. Critical micelle concentration of drug at four different temperatures was measured by surface tension and electrical conductivity measurements. The data was used to calculate surface excess concentration and thermodynamic parameters for the micellization process i.e. free energy of adsorption, free energy, entropy and enthalpy of micellization. Spectroscopic study of the drug/surfactant interaction was helpful to calculate partition coefficient, free energy of partition, binding constant and free energy of binding.