Volumetric, acoustic and spectroscopic study of 1-butyl-3-methylimidazolium trifluoromethanesulfonate with alkoxyalkanols at different temperatures

Abstract

In the present investigation, densities (ρ), speeds of sound (u) and refractive index (nD) for the binary blends of 1-Butyl-3-methylimidazolium trifluoromethanesulfonate[Bmim][OTf], an ionic liquid, with diethylene glycol monomethyl ether (DEGMME) and diethylene glycol monoethyl ether (DEGMEE) are reported over the entire range of composition, at temperatures ranging from 298.15 to 323.15K and at 0.1MPa pressure. From the experimental data, various excesses function like excess molar volume (VmE), excess isentropic compressibilities (κsE), excess molar isentropic compressibilities (Ks,mE), excess speed of sound (uE), and deviation in refractive index (ΔnD) are calculated. Excess functions are fitted with Redlich-Kister polynomial equation to obtain the binary coefficients and the standard errors. Excess partial molar volumes (V¯m,1E and V¯m,2E) and their limiting values at infinite dilution (V¯m,10,E andV¯m,20,E) are calculated from the experimental density measurements. Excess partial molar isentropic compression, K¯s,m,1E and K¯s,m,2E of both components and their respective limits at infinite dilution, K¯s,m,10,E and K¯s,m,20,E, are obtained. The nature of molecular interactions in the binary mixtures are investigated adopting FT-IR spectroscopic data especially from the view point of the associations and disassociations of intramolecular H-bondings in the alkoxyalkanol molecules by the progressive addition of the ionic liquid in the blends.