Effect of Water On Deep Eutectic Solvents: Structural Properties and Interactions with CO2

06 October 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


One of the biggest research challenges of the current time is developing technologies for removing CO2 from air. Deep eutectic solvents (DESs), specifically comprised of ionic liquids along with hydrogen bond donors, are promising for direct air capture (DAC) due to their low volatilities, high thermal stabilities, tuneable properties, and high sustainabilities. As water is inevitable in DAC, DESs designed for DAC must be able to function in the presence of water. Addition of water to DESs is believed to have a strong impact on DES properties, including hydrogen bond networks, molecular transport, and interactions with CO2. This study employs classical molecular dynamics (MD) simulations to explore the impact of water addition on the structural and intermolecular properties of DESs composed of 1-ethyl-3-methylimidazolium cations ([EMIM]) and 2-cyanopyrrolide anions ([2CNPyr]) along with three different hydrogen bond donors - ethylene glycol (EG), propylene glycol (PG), and monoethanolamide (MEA). Results show significant structural changes in the DESs due to addition of water, including enhanced interactions between CO2 and [EMIM], [2CNpyr], and MEA.


Deep eutectic solvents
ionic liquid
CO2 separations
Direct air capture
Solvent structure
classical molecular dynamics
Influence of water

Supplementary materials

SUPPORTING INFORMATION FOR: Effect of Water On Deep Eutectic Solvents: Structural Properties and Interactions with CO2
The following are the Supplementary data to this article: Section S1. System compositions, Section S2: Computed Densities for DES systems, Section S3: Mean squared displacement, Section S4.X-ray Scattering Static Structure Functions, Section S5. Centre of Mass RDFs between Cation –Anion, Section S6. Centre of Mass RDFs between Cation-HBD and Anion-HBD, Section S7. Spatial Distribution Functions, Section S8. Coordination Number, Section S9. Hydrogen Bond between DES species with Water, S10.Structural Organization Around CO2, Section S11. Centre of mass RDFs between Cation and Anion and HBDs with CO2, Section S12. Coordination Number between COM RDFs between HBDs and CO2, Section S13. Spatial Distribution Functions of HBDs around CO2, Section S14. Interaction energies between DES components with CO2.


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