Performance investigation and mechanism analysis of liquid-liquid equilibrium for 2-methylfuran and methanol with ionic liquids

The separation of 2-methylfuran (2-MF) and methanol (MeOH) azeotropes presents a critical challenge in biofuel production due to the efficiency and sustainability limitations of conventional methods. In this study, three ionic liquids (ILs)—1-ethyl-3-methylimidazolium hydrogen sulfate ([EMIM][HSO 4 ]), 1-ethyl-3-methylimidazolium thiocyanate ([EMIM][SCN]), and 1-ethyl-3-methylimidazolium dicyanamide ([EMIM][DCA])—were selected as green extractants for 2-MF – MeOH azeotropic separation. Ternary liquid-liquid equilibrium (LLE) data for the system 2-MF (1) + MeOH (2) + IL (3) were experimentally determined at 303.15 K and 101.325 kPa. The order of both distribution coefficient and selectivity is [EMIM][HSO 4 ] > [EMIM][SCN] > [EMIM][DCA]. Then, the NRTL model was subsequently employed to regress the experimental data, and the accuracy of the NRTL binary parameters was verified through the “GMcal_TieLinesLL” tool. Further mechanistic investigation integrated theoretical approaches (ESP, IGMH, RDF, and MSD analysis) with experimental validation via FT-IR spectroscopy. This combined methodology conclusively elucidates the pivotal role of hydrogen bonding in the extraction and separation process.