LAUSR

Abstract The present work aims to study the interactions of cationic imidazolium based ionic liquids i.e. 1-alkyl-3-methylimidazolium bromide ([Cnmim][Br], where n = 5 &6) with anionic surfactant sodium hexadecyl sulfate (SHS) in aqueous media employing the various techniques such as conductivity measurement, fluorescence spectroscopy, UV–visible spectroscopy and FT-IR spectroscopy. The temperature dependence of critical micelle concentration (CMC) determined using conductivity measurements at temperatures (298.15, 303.15 and 308.15) K at different concentrations (0.02, 0.05 and 0.1) wt. %, of ionic liquids (ILs) in aqueous medium was used to calculate the various thermodynamic parameters of micellization such as, standard free energy of micellization ( Δ G m 0 ), standard enthalpy of micellization ( Δ H m 0 ), and standard entropy of micellization ( Δ S m 0 ). Further, fluorescence and UV–Visible spectroscopy have been utilized to confirm the CMC values obtained from conductivity measurements, which were found to be in good agreement. A continuous increment in CMC value was observed with the increase in concentration of ILs as well as in temperature. Further FT-IR Spectroscopic studies have been done to demonstrate the structural alterations occurring in the respective mixtures.