Measurement and Modeling of Thermodynamic Properties for Ternary Mixtures Containing 1‑Butyl-3-methylimidazolium-Based Ionic Liquids with Acetophenone and Acetic or Propionic Acid

In the present work, we obtained density (ρ123), speed of sound (u 123), excess molar volume (V m123 E ), and deviation in isentropic compressibility (Δk s123) for ternary mixtures of {[BMIM]­[BF4] (x 1) + acetic acid (x 2) + acetophenone (x 3)} (mixture 1), {[BMIM]­[BF4] (x 1) + propionic acid (x 2) + acetophenone (x 3)} (mixture 2), and {[BMIM]­[PF6] (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 E and 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.