Volumetric, ultrasonic and spectroscopic studies of molecular interactions in binary mixtures of 1-butyl-3-methylimidazolium hexafluorophosphate with 2-propoxyethanol at temperatures from 298.15 to 323.15 K

Abstract

The densities, ρ ultrasonic speeds, u and refractive index nD of the binary mixtures of ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6] with 2-propoxyethanol, including those of pure liquids, have been measured over the entire range of composition at 298.15, 303.15, 308.15, 313.15, 318.15 and 323.15K and atmospheric pressure. The IR spectra of these mixtures have also been recorded at 298.15K. From the experimental data, excess molar volumes, VmE, excess isentropic compressibility, κsE, deviations in ultrasonic speed, Δu, excess molar isentropic compressibility, Ks,mE, and deviations in refractive indices, ΔϕnD were calculated and fitted using the Redlich–Kister equation. The partial molar volumes, V̅m,1 and V̅m,2, partial molar isentropic compressibilities, K̅s,m,1 and K̅s,m,2, excess partial molar volumes, V̅m,1E and V̅m,2E and excess partial molar isentropic compressibilities, K̅s,m,1E and K̅s,m,2E over whole composition range; partial molar volumes, V̅m,1° and V̅m,2°, partial molar isentropic compressibilities, K̅s,m,1° and K̅s,m,2°, excess partial molar volumes, V̅m,1°E and V̅m,2°E and excess partial molar isentropic compressibilities, K̅s,m,1°E and K̅s,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.