In the present work, we obtained density (ρ 123 ), speed of sound (u 123 ), excess molar volume (V m123 E ), and deviation in isentropic compressibility (Δk s123 ) for ternary mixtures of {[BMIM][BF 4 ] (x 1 ) + acetic acid (x 2 ) + acetophenone (x 3 )} (mixture 1), {[BMIM][BF 4 ] (x 1 ) + propionic acid (x 2 ) + acetophenone (x 3 )} (mixture 2), and {[BMIM][PF 6 ] (x 1 ) + acetic acid (x 2 ) + acetophenone (x 3 )} (mixture 3) at temperatures ranging between 293.15 and 333.15 K and at a pressure of 0.1 MPa. V m123 Eand Δk s123 values of the ternary systems were modeled with 9 predictive (no estimated parameter) and 7 correlative terms, leading to a total of 63 evaluated models. Using a standardized deviation (σ), it was possible to estimate the optimal number of parameters in the correlation, which varied from 1 to 11. The average σ for V m123 E mixture 3 was about twice the values for mixtures 1 and 2, even using more parameters for the last mixtures. For Δk s123 , σ is in the same range for the three mixtures, even though only one parameter is used in each temperature for mixture 1 and up to 11 are used in mixtures 2 and 3. These results indicate that nonideality qualitatively is in the order mixture 3 > mixture 2 > mixture 1.

In this work, we studied the intermolecular interactions of binary mixtures of 1-ethyl-3-methylimidazolium-based ionic liquids (ILs) with acetic or propionic acid. The physicochemical behavior of the binary mixtures was investigated by measuring the thermophysical properties, including the density (ρ), sound velocity (u), and refractive index (n D ), over the complete range of the IL mole fraction at T = 293.15−333.15 K and p = 0.1 MPa. The surface tension (γ) of the binary mixtures was also measured at T = 298.15 K but not determined under other studied temperatures due to the lack of a temperature controller. The excess molar volumes (V m E ), excess isentropic compressibilities (k s E ), excess sound velocity (u E ), intermolecular free length (L f ), deviation in the refractive index (Δn D ), and deviation in the surface tension (Δγ) were determined from experimental results. These parameters were further fitted to the Redlich−Kister polynomial equation. FTIR studies of pure components and binary systems at an equimolar composition were conducted to clarify results from thermodynamic properties and also analyze the intermolecular interactions occurring in the mixture. A survey on available literature data was carried out to compare with our experimental data. The selected ILs allowed us to compare the influence of the anion on the thermophysical and thermodynamic properties the mixtures.

The thermophysical properties of a series of alkyl imidazolium-based ionic liquids with acetophenone over the wide range of composition and at (293.15, 303.15, 313.15, 323.5 and 333.15) K under atmospheric pressure is reported in this study.

No abstract