Study of molecular interactions in binary liquid mixtures of [Emim][BF4] with 2-methoxyethanol using thermo acoustic, volumetric and optical properties

• The studied binary mixture is {[Emim][BF4] + 2-methoxyethanol}.
• Density, speed of sound and refractive index are measured at various temperatures at T = (298.15–328.15) K.
• Derived excess/deviation parameters indicated the existence of strong interactions.
• Dominance of specific interactions explains the observed interactions.
• IR spectral studies also support the existence of strong interactions.

Physical properties, such as density (ρ), speed of sound (u) and refractive index (nD) for pure [Emim][BF4], 2-methoxyethanol and their binary mixtures are measured over the whole composition range as a function of temperature between (298.15–328.15) K at atmospheric pressure. Experimental values were used to calculate the excess values of molar volumes (VmE), partial molar volumes (V¯mE), partial molar volumes at infinite dilution (V¯mE,∞), excess/deviation values of isentropic compressibility (κsE), acoustic impedance (ZE), free length (LfE), speeds of sound (uE), refractive index (ΔϕnD) and isobaric thermal expansion coefficient (αPE) for the binary mixtures. These excess/deviation properties are fitted to the Redlich–Kister type equation to obtain the binary coefficients and the standard deviations. A qualitative analysis of these parameters indicates strong intermolecular interactions between the liquids in study. This was further supported by IR spectroscopy.