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Ionic liquids have generated interest for efficient SO₂ absorption due to their low vapor pressure and versatility. In this work, a systematic investigation of the structure, thermodynamics, and dynamics of SO₂ absorption by ionic liquids has been carried out through quantum chemical calculations and molecular dynamics (MD) simulations. MP2 level calculations of several ion pairs complexed with SO₂ reveal its preferential interaction with the anion. Results of condensed phase MD simulations of SO₂–IL mixtures manifested the essential role of both cations and anions in the solvation of SO₂, where the solute is surrounded by the “cage” formed by the cations (primarily its alkyl tail) through dispersion interactions. These structural effects of gas absorption are substantiated by calculated Gibbs free energy of solvation; the dissolution is demonstrated to be enthalpy driven. The entropic loss of SO₂ absorption in ionic …