Thermodynamic, excess and optical studies on the intermolecular interactions of binary liquid mixtures of imidazolium based ILs

Abstract

The densities, ρ, speeds of sound, u and refractive indices, nD of binary mixtures of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide {[Bmim][NTf2]} and N-methyl-2-pyrrolidinone (NMP), including those of pure liquids, over the entire composition range were measured at temperatures (298.15, 303.15, 308.15, 313.15, 318.15 and 323.15)K and atmospheric pressure. From the experimental values, the excess molar volumes, VmE, excess isentropic compressibilities, κsE, excess speeds of sound, uE, deviations in refractive index, ΔϕnD and deviations in molar refraction, ΔRM have been calculated. The partial molar volumes, V¯m,1 and V¯m,2 and excess partial molar volumes, V¯m,1E and V¯m,2E over the whole composition range and the partial molar volumes, V¯m,1° and V¯m,2° and excess partial molar volumes, V¯m,1°E and V¯m,2°E of the components at infinite dilution have also been calculated. The variations of these parameters with composition and temperature have been discussed in terms of intermolecular interactions prevailing in these mixtures.