Modeling thermodynamic derivative properties of ionic liquids with ePC-SAFT

Abstract

In this work, ePC-SAFT was extended to predict the second order thermodynamic derivative properties of pure ionic liquids (ILs), such as isothermal and isentropic compressibility coefficients, thermal pressure coefficient, heat capacities, speed of sound, thermal expansion coefficient and internal pressure. ePC-SAFT predictions were compared with available experimental data of imidazolium-based ILs. The pure-component ePC-SAFT parameters for the IL-cations [C2mim]+, [C4mim]+, [C6mim]+ and [C8mim]+, and IL-anions [BF4]−, [PF6]− and [Tf2N]− were taken from literature in order to predict the thermodynamic derivative properties. The pure-component ePC-SAFT parameters for the IL-cations [C3mim]+, [C5mim]+, [C7mim]+ and [C10mim]+ were predicted based on linear molecular-weight-dependent relations. These estimated ePC-SAFT parameters were verified by comparing so-predicted pure-IL density as well as predicted CO2 solubility in ILs with respective experimental data. Further, these parameters were used to predict the second order thermodynamic derivative properties. The comparison of model prediction with experimental data showed that ePC-SAFT predictions were reliable in a wide temperature and pressure range.