Influence of Water on the Carbon Dioxide Solubility in [OTf]- and [eFAP]-Based Ionic Liquids

The solubility of high-pressure carbon dioxide in mixtures of ionic liquid and water was determined experimentally for 1-ethyl-3-methylimidazolium trifluoromethanesulfonate and 1-alkyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ionic liquids (where alkyl is ethyl, butyl, or hexyl). Experiments were performed at 313.15 K and/or 318.15 K, at pressures up to 10 MPa, and for various compositions (dry ionic liquids, 0.1 or 10 wt % of water), depending on the ionic liquid under investigation. It was found that the solubility of carbon dioxide in tris(pentafluoroethyl)trifluorophosphate-based ionic liquids is not affected by the water content, whereas for 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, the carbon dioxide sorption capacity is reduced by up to 10%, when 10 wt % of water is present in the system, at the same temperature and pressure.