Thermophysical, Spectral, and Theoretical Studies of Binary Systems Comprising 1-Hexyl-3-methylimidazolium Bromide and 2-Alkoxyethanols

The study of binary solutions is indispensable for many industrial purposes, particularly for developing new products, testing molecular theories, and designing processing techniques with suitable operating conditions. In this work, thermodynamic properties such as the density, viscosity, and refractive index of binary mixtures of 1-hexyl-3-methylimidazolium bromide with 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, and 2-butoxyethanol have been studied as a function of mole fraction at temperatures from 298.15 to 313.15 K at intervals of 5 K and pressure = 0.1 MPa. The excess molar volume, deviation in viscosity, excess Gibbs free energy of activation for viscous flow, deviation in refractive index, and excess molar refraction have been derived from the measured properties and fitted to the four-parameter Redlich–Kister equation. Additionally, excess molar volumes have been correlated using Graph and Prigogine–Flory–Patterson theories. Further, different viscosity relations having zero to three interaction parameters have been employed to correlate the viscosity-composition data, and their corresponding average standard deviation percentages have been computed to assess the efficiency of these correlations. The observed sign of excess properties predicts strong interactions between [HMIM]Br and 2-alkoxyethanol molecules. Moreover, Fourier-transform infrared and Raman spectra of selected systems have been examined to strengthen our experimental outcomes.