Thermodynamic study of the process of micellization of long chain alkyl pyridinium salts in aqueous solution

Abstract

[Abstract]: The molality dependence of specific conductivity of pentadecyl bromide, cetylpyridinium bromide and cetylpiridinium chloride in aqueous solutions has been studied in the temperature range of 30–45 °C. The critical micelle concentration (cmc) and ionization degree of the micelles, β, were determined directly from the experimental data. Thermal parameters, such as standard Gibbs free energy ΔG0m, enthalpy ΔH0m and entropy ΔS0M, of micellization were estimated by assuming that the system conforms to the pseudo-phase separation model. The change in heat capacity on micellization ΔCp, was estimated from the temperature dependence of ΔH0m. An enthalpy–entropy compensation phenomenon for the studied system has been found.