Molecular dynamics investigation of the interaction between volatile organic compounds and deep eutectic solvents

Mixtures of tetrabutylammonium-chloride-based deep eutectic solvent (DES) and three volatile organic compounds (VOCs) – butanal, ethanol, and toluene – have been investigated using classical molecular dynamics simulations. Various structural analyses like radial and spatial distribution functions reveal the presence of specific interactions between DES components and VOCs. The interaction between the VOC and DES components depends on the nature of the former. Both ethanol and butanal have an H-bond interaction with chloride and ethylene glycol. Tetrabutylammonium cations are present above and below the ring of toluene due to the presence of π electron cloud, and toluene also forms π hydrogen bonds with ethylene glycol. The structure of DES is not significantly affected by the absorption of VOCs, which is reflected in their radial distribution functions. Components of DES become more mobile with the addition of VOCs. The interfacial region was found to be the most favourable location for the presence of VOCs.