Characteristics of Deep eutectic solvents for CO₂ capture with Hydro effects for improvement of mass transfer

Deep eutectic solvents (DESs) prepared by mixing hydrogen bond donors (HBDs) and acceptors (HBAs) are attracting attention to use absorbents for carbon capture, storage, and utilization (CCUS) technology, but their applications in large-scale industries are limited by the scarce research in the field. When DES was used as CO₂ absorbent, the use of appropriate HBAs and HBDs is critical for application. In this study, choline chloride (ChCl, as the HBA) was mixed with five different HBDs and diluted to 20 wt% water (W) for improvement of mass transfer, and their CO₂ absorption capacities and physicochemical properties were analyzed. Urea (U), ethylene glycol, glycerol, and malic and levulinic acids were used as HBDs due to their various functional groups. ChCl:U:W can be a potential alternative to conventional alkanolamine absorbents for use in CCUS among the studied DESs, as its absorption capacity was superior to those of the other DESs. Increase of surface tension and decrease of density and viscosity were observed by addition of water on all of DESs. Additionally, absorption rate increased via water addition. This study can contribute to the future development of a more efficient CCUS technology using solvent alternatives that are more suitable for future environmental challenges.