Non-ideality of Solutions of NH3, SO2, and H2S in Ionic Liquids and the Prediction of Their Solubilities Using the Flory-Huggins Model

The non-ideality of solutions of light compounds, such as SO2, NH3, and H2S, in ionic liquids (ILs) is studied here using experimental vapor-liquid equilibrium (VLE) data previously published. The data available for systems of ILs with SO2, NH3, and H2S show that these systems present negative deviations to the ideality in the liquid phase and that these deviations are dominated by entropic effects. It is shown here that, for the solutions of SO2 and NH3 in ILs, the deviations from ideality and the gas solubility can be predicted using the Flory-Huggins model. For H2S, a positive deviation to the non-ideality that arises from the enthalpic effects somewhat decreases the quality of the description of the experimental data by the Flory-Huggins model predictions.