Experimental and Theoretical Insights into CO₂ and N₂ Capture Using Natural Hydrophobic Deep Eutectic Solvents at...

This study explores three binary natural hydrophobic deep eutectic solvents (HDESs) for capturing carbon dioxide (CO₂) and nitrogen (N₂) at high pressures. The HDES systems, comprising linoleic acid (LnA) as a hydrogen-bond donor (HBD) and camphor (CAM), citral (CIT), or piperitone (PIP) as a hydrogen-bond acceptor (HBA), were synthesized and characterized for density, viscosity, conductivity, surface tension, and contact angle. High-pressure gas absorption experiments demonstrated CO₂ and N₂ capture, achieving absorption rates of ∼62%-92% within 100 s at 10-30 bar. At 25 bar, a mole fraction absorption of 0.47 matched the performance of aqueous monoethanolamine (MEA) at 25 °C. Among the HDESs, CAM-LnA (1:1) exhibited the highest CO₂ selectivity at 2.5 and 5 bar, with values of 41.4 and 44.2, respectively. The conductor-like screening model for real solvents (COSMO-RSs) method predicted eutectic points and gas absorption, while molecular dynamics simulations assessed gas interactions at the molecular level. The results underscore the potential of HDES for high-pressure gas capture, providing insights into their production, characterization, and applications.