In recent years, environment problems have been a hot issue of concern to the public. Chlorinated volatile organic compounds such as dichloromethane (DCM) have been a serious threat to the public health and environment as hazardous chemical substances. Solving these problems has become an urgent issue in nowadays society. Ionic liquids (ILs) are supposed to be potential solvents to absorb gases due to their unique structures and properties, which have exhibited excellent absorption capacity in NH3, SO2, CO2 and other gases. In this paper, a series of conventional ILs including [Bmim][BF4], [Bmim][PF6], [Bmim][DCA], [Bmim][SCN], [Bmim][NTf2], [Emim][SCN], [BPy][SCN] were synthesized and used as absorbents for dichloromethane (DCM) capture at different temperatures and partial pressures. The absorption capacities of DCM by ILs were measured by a highly sensible microbalance-intelligent gravimetric analyzer (IGA). It was found that [Bmim][SCN] has the highest absorption capacity to DCM (1.46 g/g, 303.15 K, 60 kPa) among these investigated ILs, and the absorption capacity of [Bmim][SCN] had no obvious decline after five absorption?desorption cycles. The densities and viscosities of [Bmim][SCN] with different mass fraction of DCM absorbed were measured in this work as well. And with the increase of the mass fraction of DCM absorbed, the density of DCM absorbed [Bmim][SCN] increased slightly, while the viscosity decreased dramatically. In addition, mechanism of DCM absorption by [Bmim][SCN] was investigated through FT-IR and 1H?NMR, implying the interaction between DCM and [Bmim][SCN] was physical interaction. Furthermore, the interactions between cations or anions of ILs and DCM were investigated by quantum chemical calculation, which demonstrated that the anions of ILs had a more significant influence on the absorption capacity than cations, on account of the strong hydrogen bond interaction between anion and DCM, which has a great agreement with the results of experiment. This work will provide a new sight for designing more competitive ILs for DCM capture.
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