Micellization Parameters of Six Gemini Quaternary Ammonium Surfactants from Measurements of Conductivity and Surface Tension

The micellization of six Gemini quaternary ammonium surfactants aqueous solutions has been investigated from measurements on specific conductivity as a function of surfactant concentration at different temperatures from (298.15 to 323.15) K. The micellization parameters such as the critical micellar concentration (CMC) and the degree of counterion dissociation (beta), Gibbs free energy (Delta G(mic)), enthalpy (Delta H-mic), and entropy (Delta S-mic) of micellization are then obtained. It is shown that the conductometry measurements provide agreement of the CMC values at 298.15 K with the surface tension studies. With the rise of temperature, the values of CMC and beta increase, while Delta G(mic) changes little. The linear plots of T Delta S-mic versus Delta H-mic show the effects of enthalpyentropy compensation. The length of alkyl chain and the spacer group of the Gemini surfactant have significant influences on micellization parameters.