Effect of 1-Pentanol on the Thermodynamics of the Micellization of Hexadecyltrimethylammonium Bromide in Aqueous Solutions

Resumo

The thermodynamic parameters (ΔH, ΔG, and ΔS) of the micellization of hexadecyltrimethylammonium bromide (CTAB) in aqueous solutions of 1-pentanol at 298.15 and 313.15 K are measured via micelle destruction. Critical micelle concentrations CMC 1 and CMC 2 at different concentrations of pentanol are determined. It is found that adding pentanol to a solution at 313.15 K does not affect the entropy of micelle formation, which is ΔS in pure water. A linear compensation relationship between the ΔH and ΔG values is revealed. It is shown that the entropy of a solution at 298.15 K falls upon adding pentanol, and the compensation relationship between the ΔH and ΔS values is in this case similar to the one obtained upon varying the temperature of a solution.