Carbon dioxide and hydrogen sulfide capture by menthol-based deep eutectic solvents: Effects of sorbent structure, composition, gas pressure, and gas polarity

The phenomenon of global warming is linked to excessive industry-associated greenhouse gas emissions. Innovative sorbents are expected to foster green technologies, in which no adverse environmental influences are included. We herein report classical molecular dynamics (MD) simulations to evaluate the absorption of carbon dioxide (CO₂) and hydrogen sulfide (H₂S) by the newly developed deep eutectic solvents (DESs). The novel DESs represent binary mixtures of menthol (MEN) and diamines (hexyl-ethylene-diamine, HEX, and nonyl-ethylene-diamine, NON,). The simulations revealed that both DESs exhibit a higher affinity to CO₂ rather than to H₂S due to larger partial atomic electrostatic charges on the oxygen atoms. The increase in pressure resulted in a linear boost in the gas capacities of HEX/MEN and NON/MEN. In turn, no synergistic effect was detected while investigating CO₂/H₂S simultaneous absorption. The performance of HEX/MEN as an absorbent is somewhat higher as compared to that of NON/MEN in the case of H₂S and within the computation uncertainty in the case of CO₂. The revealed potential of HEX/MEN and NON/MEN to capture CO₂ and H₂S suggests that novel interesting gas scavengers were identified and comprehensively characterized.