Thermodynamic Study of Temperature and Dimethyl Formamide on the Micellization of Hexadecyltrimethylammonium Bromide

The aggregation behavior of surfactants in aqueous–organic mixed solvents has been thesubject of much attention in the past few years [1-3]. In this work, the effect of dimethylformamide on the critical micelle concentration (CMC) of hexadecyltrimethylammonioumbromide (HTAB) have been investigated by conductometeric measurement method at T= (298.2,308.2 and 318.2) k. The CMC values of HTAB were measured in pure water and water +dimethyl formamide mixtures containing 10, 20 and 30% dimethyl formamide.Thethermodynamic properties such as the free energy change of micellization (ΔG˚(mic)), the entropychange of micellization (ΔS˚(mic)), and the enthalpy change of micellizaton (ΔH˚(mic)) have beenobtained for the studied surfactant solutions with or without organic solvent by using themeasured CMC data. The obtained results show that the CMC values increase with increasingtemperature and dimethyl formamide concentration.

Keywords:

Thermodynamic Study , Hexadecyltrimethylammonium Bromide , Micellization , Dimethyl Formamide