Liquid-liquid phase behavior for water + 2,2-difluoroethanol with three imidazole-based ionic liquids

Abstract 2,2-difluoroethanol (DFE) is a significant fine chemical in chemical industry. During its applications, an aqueous solution is often observed. Because DFE and water will form azeotropic mixture, it is infeasible to regenerate DFE from the mixture (DFE + water) by general distillation. In this research, for regenerating 2,2-difluoroethanol from its aqueous mixture by extraction, three hydrophobic imidazole-based ionic liquids (ILs), 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Hmim][NTf2]), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][NTf2]) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][NTf2]) were picked as the extraction agents. The liquid–liquid phase behavior of the systems (water + DFE + ILs) were explored at 298.15 K and 101.3 kPa. The NRTL model was applied to regress the determined tie-line data. To assess the separating power of the three ionic liquids, selectivity (S) and distribution coefficient (D) for ILs were computed and compared. In addition, the σ-profiles, interaction energy, hydrogen bond length between the ionic liquids and (DFE/water) were computed to ascertain the interactions between the ILs and (DFE/water).