Molecular Modeling of HFC Separation in Fluorinated Ionic Liquids: A SAFT-VR Mie Study

Given the critical role of hydrofluorocarbons (HFCs) in the refrigeration industry, their recovery is crucial to promoting circular economy strategies and reducing greenhouse gas emissions. In this work, the SAFT-VR Mie equation of state is applied to describe the solubility of R32, R125, and R134a in ionic liquids (ILs) with varying degrees of fluorination, which are proposed as potential absorbents for gas separation. ILs are treated as associating species, with multiple sites accounting for charge delocalization. The model provides an excellent description of density and viscosity, the latter obtained through the Helmholtz scaling theory. In addition, the effect of polarity is explicitly accounted for in the HFCs. As a result, their solubility in ILs is quantitatively reproduced using a single, temperature-independent binary parameter, ensuring a strong predictive capability. Furthermore, the working capacity and competitive selectivity of the components in commercial R410A and R407F blends are predicted, revealing significant differences in performance depending on the solvent composition and fluorination level. Additional properties, such as regeneration enthalpy and viscosity, are also evaluated to identify the most promising ILs for refrigerant recovery. Overall, this study demonstrates the capability of SAFT-VR Mie as a robust molecular-based tool for solvent screening in sustainable HFC separation technologies.