Absorption performance and mechanism of volatile organic compounds by phosphonium ionic liquids with different anions

Abstract BACKGROUND The emission of volatile organic compounds (VOCs) seriously harms the environment and human health. The prevention and control of VOC pollution is a major challenge in the research field. Aiming at VOC pollution treatment using green solvents, the absorption of trichloromethane by synthesized tributyl(propyl)phosphonium bis(trifluoromethylsulfonyl)imide (P 4443 Tf 2 N), tributyl(propyl)phosphonium tetrafluoroborate (P 4443 BF 4 ), tributyl(propyl)phosphonium trifluoroacetic acid (P 4443 CF 3 COO) and xylene by trioctyl(propyl)phosphonium bis(trifluoromethylsulfonyl)imide (P 8883 Tf 2 N) and trioctyl(propyl)phosphonium tetrafluoroborate (P 8883 BF 4 ) were experimentally measured. The mechanism of trichloromethane and xylene absorption by phosphonium‐based ionic liquids (PILs) with different anions was further discussed through simulation calculation. RESULTS PILs process excellent absorption capacity, such as P 4443 CF 3 COO, with static saturation absorbing capacity up to 2.843 g g −1 for trichloromethane. PILs have a certain selective absorption ability for xylene, which has the highest absorption for o ‐xylene, reaching 1.462 g g −1 . The absorption energy data also prove that CF 3 COO − anion preferentially interacts with trichloromethane. Combined with the most stable structures of VOCs absorbed by PILs, the results of the Mulliken charge and frontier molecular orbitals indicate that PIL anions play a major role in chlorinated alkanes, and form hydrogen bonds with them. In addition, the cation can form CH···π bond interaction with xylene. CONCLUSION The experimental and calculated results showed that PILs are a promising adsorbent for trichloromethane and xylene. The study provides a reference for PILs designed to deal with VOCs in the future. © 2024 Society of Chemical Industry (SCI).