Molecular Origins of Site-Specific CO2 Absorption in Hydrated Deep Eutectic Solvents
Year: 2026
Type: preprint
Abstract: Deep eutectic solvents (DESs) have emerged as promising candidates for CO 2 capture because of their highly tunable structures and CO 2 absorption capacities. However, their behavior under practical operating conditions remains poorly understood. In particular, the effect of water on DES structure and their CO 2 absorption capacity remains unclear. In this work, we use free energy perturbation (FEP) and molecular simulations to determine the CO 2 absorption capacities and transport properties of hydrated hydrophilic and hydrophobic DESs. Our results show that increasing water concentration decreases viscosity but also makes CO 2 solvation less favorable in both DESs, revealing a trade-off between transport properties and CO 2 absorption capacity. This trade-off is more favorable for the hydrophobic DES, which shows a substantial reduction in viscosity while maintaining a negative CO 2 solvation free energy. In contrast, the solvation free energy of the hydrophilic DES increases more substantially, becoming positive at 15 wt% H 2 O. Structural analysis reveals that these differences arise from distinct hydration and CO 2 solvation mechanisms in the two DESs. In the hydrophilic DES, CO 2 preferentially localizes around the Br – anion under dry conditions. Upon hydration, water blocks the anionic site, and the preferred CO 2 solvation site shifts to the cation.
Source: ChemRxiv
Authors: Deepak Kumar Panda, Soumik Das, Salman A. Khan
Institution: Indian Institute of Technology Kanpur
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
SDG: Climate action
Open Access status: green
OpenAlex ID: W7212162980