Viscosity Modeling of Pure Ionic Liquids and Their Binary Mixtures Using a Modified Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) Equation of State and Entropy Scaling

Ionic liquids (ILs) have garnered significant interest due to their unique physicochemical properties and promising application potential. Among these properties, viscosity plays a critical role in determining IL performance. In this study, the entropy scaling method in combination with the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state (EoS) is employed to build a correlational model for pure ILs and a predictive model for IL binary mixtures. Model parameters for the PC-SAFT EoS were regressed against a comprehensive experimental data set comprising 12,239 density data points. A complete set of PC-SAFT molecular parameters for 45 ILs is reported. For 31 pure ILs, covering temperatures from 259.50 to 438.15 K and pressures from 0.6 to 4011.0 bar, the model achieves an average absolute relative deviation (AARD) of 7.72%. For 9 IL binary mixtures at atmospheric pressure, with temperatures ranging from 253.15 to 363.15 K, the AARD is 14.20%.