Measurement of\nVapor–Liquid Equilibrium for\nDichloromethane + Alkyl Sulfate-Based Ionic Liquid Systems

Ionic liquids (ILs) show great potential for the treatment\nof dichloromethane\n(DCM)-containing waste gases, but currently there are limited data\non the vapor–liquid equilibrium (VLE) of DCM + IL systems.\nThis work uses headspace gas chromatography (HS-GC) to determine the\nisothermal VLE data of the DCM + [Epy][EtSO<sub>4</sub>] and DCM +\n[Emim][EtSO<sub>4</sub>] systems at 308.15 K, 313.15 K, 318.15 K,\n323.15 K, and 328.15 K. The nonrandom two-liquid (NRTL) and universal\nquasi-chemical correlation activity coefficient (UNIQUAC) models are\nused to regress the VLE data. The results show that the fitting average\nrelative deviations (ARDs) of the DCM + [Epy][EtSO<sub>4</sub>] and\nDCM + [Emim][EtSO<sub>4</sub>] systems to the NRTL model were 6.97%\nand 7.95% and the fitting ARDs to the UNIQUAC model were 6.10% and\n6.28%, respectively. The fitting effects of the UNIQUAC models for\nboth systems were better than those of the NRTL model. With the models,\nthe calculated activity coefficients of DCM were all less than 1,\nindicating that the solutions exhibited negative deviations from Raoult’s\nlaw, and the nonideality of the solutions increased with increasing\nIL concentration.