A novel approach based on detailed structural and molar free volume analyses to characteristics of deep eutectic solvents specialized for CO2 absorption

Abstract

This study presents a novel approach based on structural and molar free volume analyses to characterize deep eutectic solvents (DESs) with functional groups possessing CO2 affinity based on analytical prediction and data. Although DESs have garnered attention due to their high tunability and applicability in various fields, there is paucity of literature containing their detailed analyses. In this investigation, HBDs with amino (–NH2), carbonyl (CO), and ether (R-O-R') groups were chosen to determine the effect of functional groups on the CO2 absorption capacity and structural properties of DESs. Based on FT-IR and 1D/2D NMR measurements on DESs, it was confirmed that the hydrogen used for the formation of hydrogen bonds exhibited a distinct property and that DESs were successfully formed. In addition, the DES including tetraethylammonium bromide, 3-amino-1-propanol, and water with an amino group exhibited a high capacity for chemical CO2 absorption. In the case of the DES, structural configuration prediction was proposed using the chemical CO2 absorption capacity. The proportional relationship between the physical CO2 absorption and molar free volume of DESs was also confirmed using analytical data. Finally, these novel approaches to DESs can be used as a guide for applying and developing new DESs with structural properties.