Temperature and composition dependence of the volumetric and acoustic properties of ionic liquid [emim][HSO 4 ] with polar protic and aprotic co-solvents

Abstract In the present paper, we report new experimental data on density ( ρ ) and speed of sound ( u ) in binary liquid mixtures of 1-ethyl-3-methylimidazolium hydrogen sulphate, [emim][HSO 4 ] with polar protic solvents ethanol (EtOH) and 1-propanol (n-PrOH) and aprotic solvent, dimethyl sulphoxide (DMSO) over the complete range of mole fraction at 298.15 K ≤  T ≤ 313.15 K, every 5 K, and 0.1 MPa pressure. The mixing behaviour of the binary systems of [emim][HSO 4 ] with EtOH, n-PrOH, and DMSO has been studied by computing the excess volumes ( V E ) and excess isentropic compressibilities ( κ s E ) utilizing the measured densities ( ρ) and speeds of sound ( u ). Further, the excess functions V E and κ s E are correlated with mole fraction, using Redlich-Kister equation to derive the fitting parameters. For the systems studied, the excess thermodynamic properties ( V E and κ s E ) are found to be negative over the whole range of composition at investigated temperatures. Also, the experimental results are discussed in terms of ion-ion, ion–dipole, hydrogen bonding interactions and interstitial accommodation between component molecules in the binary liquid mixtures. Moreover, the temperature dependence of the physicochemical and excess properties has been studied.