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Indexed by:期刊论文

Date of Publication:2010-10-01

Journal:JOURNAL OF SOLUTION CHEMISTRY

Included Journals:SCIE、Scopus

Volume:39

Issue:10

Page Number:1501-1508

ISSN No.:0095-9782

Key Words:Thermodynamic properties; Critical micelle concentration; CTAC; EG

Abstract:To understand the thermodynamic characteristics of cationic surfactants in binary mixtures, the aggregation behavior of hexadecyltrimethylammonium chloride (CTAC) has been investigated in ethylene glycol (EG) + water solvent mixtures at different temperatures and EG to water ratios. The critical micelle concentration (CMC) and degree of counter ion bonding (beta) were calculated from electrical conductivity measurements. An equilibrium model for micelle formation was applied to obtain the thermodynamic parameters for micellization, including the standard Gibbs energies of micellization (Delta G degrees(mic)), standard enthalpies of micelle formation (Delta H degrees(mic)) and standard entropies of micellization (Delta S degrees(mic)). Our results show that Delta G degrees(mic) is always negative and slightly dependent on temperature. The process of micellization is entropy driven in pure water, whereas in EG + water mixtures the micellization is enthalpy driven.