Comparative study of physical properties of binary mixtures of halogen free ionic liquids with alcohols

Highlights: • Physical properties of binary mixtures of halogen free ILs with C₃, C₄ and C₅ were invetigated. • Densities, refractive indices and speed of sound were measured. • V^E, K_s^E, u^D and n_D^E were calculated using the experimental data. • Speed of sound data were analyzed using different theories and relations. • Different mixing rules were used to predict the experimental refractive indices. - Abstract: Densities, refractive indices and speeds of sound along with their excess or deviation properties for both 1,3-dimethylimidazolium methylsulfate ([dmim][MeSO₄]) and 1-ethyl-3-methylimidazolium methylsulfate ([emim][MeSO₄]) with 1-propanol, 1-butanol and 1-pentanol over the entire range of mole fraction are reported at temperatures ranging from 298.15 K to 313.15 K and atmospheric pressure. Isentropic and excess isentropic compressibilities for both ionic liquids with 1-alcohols were calculated from the experimental results. Excess and deviation properties were further correlated using the Redlich-Kister polynomial. The measured speeds of sound were compared to the values obtained from Schaaffs' collision factor theory, Jacobson's intermolecular free length theory of solutions and Nomoto's relation. In addition, the experimentally obtained refractive indices were compared to the calculated values using Lorentz-Lorenz, Dale-Gladstone and Eykman mixing rules.