Enhancing aromatic VOCs capture using randomly methylated β-cyclodextrin-modified deep eutectic solvents

Abstract

Deep eutectic solvents (DESs) were regarded as promising absorbents in many absorption processes. Here, we use randomly methylated β-cyclodextrin (RAMEB) to further improve the absorption capacity of DESs for aromatic VOCs. We found benzene and toluene vapor pressures obviously decreased after adding 2% RAMEB (molar fraction) to DESs. Dynamic absorption experiments also confirmed this enhancement effect; the dynamic absorption efficiency for benzene and toluene increased by 6.12% and 9.23%, respectively, at a 5 mL/min solvent rate. Water was used to reduce the viscosity of DESs; the humidity and regeneration stability were evaluated experimentally. At the molecular level, the strong host–guest interactions between RAMEB and aromatic VOCs were identified as the main reason for improving the absorption capacity of DESs. Additionally, the roles of hydrogen bond donor and acceptor molecules were analyzed. π–π stacking and CH–π interactions were also identified as significant contributors to the aromatic VOCs absorption process.