Thermodynamic and acoustic properties of binary mixtures containing 2-methyl-2-butanol, isopropyl ether and heptane: experimental study and modelling with PC-SAFT and Peng–Robinson equations

Densities (p) and speed of sound (u) were measured as a function of mole fraction for three binary mixtures: 2-methyl-2-butanol (1) + isopropyl ether (2), 2-methyl-2-butanol (1) + heptane (2) and heptane (1) + isopropyl ether (2), at temperature of 298.15 K and 313.15 K and at a pressure of 0.1 MPa. Measurements were performed using an Anton Paar Digital vibrating-tube densimeter and a speed of sound. From the experimental data, excess molar volume (VE) deviation in speed of sound (Δu) isentropic compressibility (ks) and deviation in isentropic compressibility (Δ) were calculated and correlated using the Redlich−Kister polynomial. Additionally, the experimental densities were modelled using the Peng−Robinson and PC-SAFT (Perturbed-Chain Statistical Associating Fluid Theory) equations of state (EoS). The PC-SAFT model showed excellent agreement with the experimental data, whereas the Peng–Robinson EoS provided less accurate predictions, particularly for mixtures exhibiting strong non-ideal behaviour. These results demonstrate the superior capability of the PC-SAFT model in describing the thermophysical properties of associating and non-ideal liquid systems.