Effective VOCs abatement using supramolecular deep eutectic solvents

A strategy to absorb volatile organic compounds (VOCs) using supramolecular deep eutectic solvents (SUPRADES) was explored from partition coefficient experiments to quantum chemical calculations. Several novel SUPRADES were prepared using cyclodextrins, among which the one based on randomly methylated (3-cyclodextrin (RAMEB) and diethylene glycol (DEG), exhibits the best fluidity. The obtained partition coefficient revealed that the combination of RAMEB or low methylated-(3-cyclodextrin (CRYSMEB) and DEG significantly improves the ability of DEG to absorb tert-butylcyclohexane (TBCH) and limonene. In particular, RAMEB-based SUPRADES (RDEG) solubilized up to 19.6 times more TBCH than pure DEG. Absorbent recycling tests confirmed RDEG's structural stability and high absorption efficiency, achieving a TBCH absorption ratio of 99.8%. Then, several weak interaction analysis methods were applied to explain the experimental results and elucidate the absorption mechanism. RAMEB and DEG were found to interact with considerable hydrogen bonds. The minima of van der Waals potential are concentrated in the cavity of cyclodextrins, which enables cyclodextrins to form stable inclusion complexes with TBCH through dispersion interactions. Moreover, the enhanced absorption of RDEG is attributed to the interaction between RAMEB and TBCH, which is much stronger than that between DEG and TBCH. The obtained results demonstrate that cyclodextrins are promising additives for traditional absorbents to enhance VOCs abatement.