Solubilization and physicochemical parameters of 2-chloro and 4-chlorophenol in micellar media of cetyltrimethylammonium bromide and sodium dodecyl sulphate at different temperatures

Abstract

Solubilization and thermodynamic parameters of 2-chloro and 4-chlorophenol in micellar media of Cetyltrimethylammonium bromide (CTAB) and Sodium dodecyl sulphate (SDS) are elaborated in this study. The effect of the addition of 2-chloro and 4-chlorophenol on the critical micelle concentrations (CMCs) of CTAB and SDS was investigated by using the conductivity method at different concentrations (5 mmolL−1 to 25 mmolL−1) and temperatures (25 °C to 45 °C). The plot of specific conductance versus concentration of surfactant was used to determine CMC value. The CMC values of CTAB and SDS were observed to decrease, and thus the addition of 2-chloro and 4-chlorophenol favors micellization. In addition, it was observed that the CMC values of CTAB and SDS gradually increased with an increase in temperature. Various types of thermodynamic parameters such as standard Gibbs free energy of micellization (ΔGm°), standard enthalpy of micellization (ΔHm°) as well as standard entropy of micellization (ΔSm°) were determined and explained thoroughly to investigate the interactions between additives and surfactant. The magnitudes of ΔGm°andΔHm° were shown to be negative in the whole system, which shows that the processes of micellization were energetically spontaneous and exothermic. The thermodynamic parameters of transfer (ΔGm.tr°, ΔHm.tr° and ΔSm.tr°) from water to 2-chloro and 4-chlorophenol were also calculated and discussed with appropriate reasoning.