Imidazolium-Based Ionic Liquids Introduced into π-Electron Donors: Highly Efficient Toluene Capture

Aromatic hydrocarbons are considered a class of extremely hazardous atmospheric pollutants of volatile organic compounds (VOCs). Toluene is a typical aromatic VOC representative, and its removal has a significant contribution to the treatment of air pollution. In this work, two imidazolium-based ionic liquids (ILs) introduced into π-electron donors, [PhCH2MIM][Tf2N] and [AMIM][Tf2N], were designed and synthesized to capture toluene for the first time, and it was found that their performances of toluene capture are obviously enhanced when compared with the common IL [EMIM][Tf2N] in a continuous experiment. In particular, [PhCH2MIM][Tf2N] presents the most excellent capture capacity among all ILs, and the toluene content of the outlet gas is decreased as 2.2 ppm at ambient temperature and pressure with fresh [PhCH2MIM][Tf2N] as an absorbent. Moreover, the microscopic mechanisms regarding the significant improvement for performance of toluene capture were systematically investigated and clarified from the multiple insights of quantum chemistry (QC) and molecular dynamics (MD). Overall, the proposed ILs were considered as promising green absorbents to achieve highly efficient toluene capture, and the design concept could also provide valuable guidance to develop new green and efficient task-specific separation agents for capturing other aromatic VOCs.