Micellization of Dodecyltrimethyl Ammonium Bromide in Pure and Binary Solvent System of Water and Ethylene Glycol: A Thermodynamic Approach

Abstract

Despite extensive studies made on surfactant since its potential for wide variety of applications, exploring the micellization of DTAB in pure solvent and in binary solvent systems of various compositions of water and ethylene glycol at different temperatures have been studied via thermodynamic approach due to the industrial applications which are largely depend on it. From conductivity measurements, the critical micelle concentration and degree of ionization were determined and a phase separation model which gives quantitative theoretical interpretation of thermodynamic parameters of micellization to evaluate the free energy, enthalpy and entropy of micellization for ionic surfactant. On the basis of results, increase of CMC and degree of counter ion dissociation with temperature and solvent composition has been discussed from thermodynamic analysis that the process is spontaneous and exothermic but micellization is less favourable in binary solvent system compared to pure water. The ΔSom values for aqueous solution of DTAB are higher than that of binary solvent systems that micellization is favoured by entropy gain in aqueous solution.