Excess thermodynamic properties of binary mixtures of ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) with alkoxyalkanols at several temperatures

Physical properties such as densities, ρ, speed of sound, u, and refractive indices, n, have been measured for the binary mixtures of ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim][PF6] with diethylene glycol monomethyl ether (DEGMME), propylene glycol monomethyl ether (PGMME) and propylene glycol monoethyl ether (PGMEE) over the whole composition range at atmospheric pressure. Experimental densities have been used to estimate excess molar volume VmE. Changes in isentropic compressibility, ΔκS, have been estimated by using experimental speed of sound and density values. Experimental refractive indices values have been used to calculate the deviation in refractive indices, Δφn, and molar refraction, ΔxR. Excess properties are fitted to the Redlich-Kister polynomial equation to obtain the binary coefficients and the standard errors. Apparent molar volume and apparent molar compressibility at infinite dilution, Vφ,i∞ and Kφ,i0 have been calculated to gain information about solute-solvent interactions. The results are compared with our earlier studies concerning the binary mixtures of [bmim][PF6] with alkoxyethanol or poly ethers.