Ionic liquid screening for dichloromethane absorption by multi-scale simulations

•Multi-scale investigation framework on ionic liquids was established.•Dichloromethane absorption in ionic liquids was systematically evaluated.•[C2MPip][C1COO] was screened as optimal ionic liquid for dichloromethane absorption. Ionic liquids (ILs) have been proposed as potential solvents for absorbing dichloromethane (DCM), while screening a promising IL with high absorption performances from numerous ILs remains challenging. In this work, a framework of multi-scale investigation on DCM absorption using ILs was established. A screening method based on COSMO-RS model that optimized by 79 reported experimental data points was proposed, and the effect of cationic and anionic structures on DCM absorption and the mechanisms were systematically studied combining quantum chemical calculation. Based on the above results, 1-ethyl-1-methylpiperidinium acetate ([C2MPip][C1COO]) was determined as the optimal IL for DCM absorption with Henry’s Constant of 3.29 kPa. The screened IL was further evaluated through process simulation comparing to the conventional IL and traditional organic solvent. The annual variable operation cost of [C2MPip][C1COO]-based process for DCM absorption was the lowest among the studied cases, showing broad prospects in applications.