Mechanisms of CO2 Absorption in Amino Acid-Based Deep Eutectic Solvents: Insights from Molecular Dynamics and DFT Calculations
Journal
The Journal of Physical Chemistry B
Journal Volume
129
Journal Issue
23
Start Page
5779
End Page
5787
ISSN
1520-6106
1520-5207
Date Issued
2025-06-12
Author(s)
Abstract
This study explores the mechanisms of CO2 absorption in two amino acid-containing deep eutectic solvents (DESs) through molecular dynamics (MD) simulations and density functional theory (DFT) calculations. The MD simulations, which focus mainly on physical absorption, reveal that alanine-based DES (Ala DES) exhibits higher CO2 solubility than l-arginine-based DES (l-arg DES), attributed to stronger physical absorption. Furthermore, the hydrogen bond donor paired with the amino acids is identified as a critical factor for enhancing physical absorption efficiency. DFT calculations, which account for chemical absorption, investigate two reaction pathways: single-molecule reactions involving intramolecular proton transfer and two-molecule reactions involving intermolecular proton exchange. While Ala DES does not exhibit spontaneous chemical absorption, l-arg DES demonstrates such reactions, leading to the formation of carbamic acid or carbamate (ΔG < 0), indicative of CO2 capture through chemical interactions. Consequently, Ala DES primarily relies on physical absorption, whereas l-arg DES utilizes multiple reactive sites for chemical absorption. These results are consistent with experimental findings, which show that l-arg DES achieves higher CO2 solubility under atmospheric conditions. Overall, our study highlights the interplay between DES components and reactivity in enhancing CO2 capture efficiency.
Publisher
American Chemical Society (ACS)
Type
journal article