Molecular Origins of Site-Specific CO2 Absorption in Hydrated Deep Eutectic Solvents
- 1Department of Chemical Engineering
- 2Indian Institute of Technology Kanpur
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.
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BibTeX
@misc{panda2026molecular,
title = {{Molecular Origins of Site-Specific CO2 Absorption in Hydrated Deep Eutectic Solvents}},
author = {Deepak Kumar Panda and Soumik Das and Salman A. Khan},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008638/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008638/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Molecular Origins of Site-Specific CO2 Absorption in Hydrated Deep Eutectic Solvents
AU - Deepak Kumar Panda
AU - Soumik Das
AU - Salman A. Khan
PY - 2026
DA - 2026/09/10
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008638/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008638/v1
AB - 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.
ER -