Salting out effects on adsorption and micellization of three imidazolium-based ionic liquids at liquid–liquid interface

The effects of sodium chloride and potassium chloride electrolytes on adsorption and micelle formation of three amphiphilic ionic liquids (ILs), 1-alkyl-3-methylimidazolium chloride, [Cnmim][Cl], n = 6, 7 and 8, at the toluene-water interface were investigated. Temperature was fixed at 298.2 K. Due to interface activity, the used ILs significantly reduce the interfacial tension and in the order of their alkyl chain length. The presence of electrolytes results in the salting out effects and intensifies reducing the interfacial tension and micelle concentrations of ILs. To fit experimental data, the Frumkin adsorption isotherm was satisfactorily applied below the critical micelle concentrations of the ILs. As a result, the adsorption parameters including adsorption tendency and saturated interface excess rise to higher levels and the electrostatic repulsion between the adsorbed IL molecules declines in the presence of electrolytes; however, the variations are more significant with sodium chloride because of smaller and more hydrated cation.