Imidazolium ionic liquids as toluene vapor absorbent were evaluated by a molecular screening method based on the COSMO-SAC model. A s-map was established for hundred common imidazolium ionic liquids composed of N

N'-dialkylimidazolium cation and an anion. Absorption potential of ionic liquids to toluene vapor at 303.15 K was calculated from the s-map and was used as thermodynamic evaluation criterion to screen absorbents. Experimental measurements on saturated absorption of toluene vapor in six ionic liquids showed consistent results with these of molecular screening

which verified reliability of this molecular screening method. Interaction energy of ionic liquid cation and toluene was calculated by Gaussian 09 software. Subsequently

effects of kinetic factors such as vapor inlet concentration and velocity were explored. An initial toluene absorption by ionic liquid reached to 96.2% under temperature of 303.15 K

inlet concentration of 10000 mg·m-3

and inlet velocity of 0.05 m3·h-1. Further study indicated that toluene absorption was almost not changed with increasing number of repeated use cycles of ionic liquid absorbents.