Accurate modeling of CO₂ solubility in ionic liquids using a cubic EoS⊥

During the past decade, various experimental studies have shown that ionic liquids exhibit interesting and attractive thermo-physical properties such as extremely low volatilities, a high thermal stability, and ionic conductivity as well as high gas solubilities. It is in the latter where the use of an ionic liquid as gas separation media seems to be very promising particularly for the capture/sequestration of carbon dioxide (CO₂) which has been shown to be highly soluble in ionic liquids as compared with other gases. Recently, a significant amount of experimental work has appeared in the literature dealing with the solubility of CO₂ in several ionic liquids at different temperature and pressure conditions. A detailed analysis of these works reveals that the highest solubilities of CO₂ have been exhibited in ionic liquids having cations of the imidazolium type together with anions of the [TF₂N] type. The purpose of this work is to present a formal modeling approach of the CO₂ solubility in the aforementioned ionic liquids by the use of a cubic equation of state (Soave or Peng-Robinson) coupled with modern mixing rules of the Wong-Sandler type. The resulting modeling approach proves to be able to correlate and/or predict the CO₂ solubility in ionic liquids over diverse conditions of temperature, pressure, and solute composition.