CO2 capture with hydrophobic halogen-free natural deep eutectic solvents: Perturbed-Chain Statistical Associating Fluid Theory modeling and molecular insights

This work systematically investigates CO₂ capture with hydrophobic halogen-free natural deep eutectic solvents (NADES) as absorbents from both thermodynamic and molecular perspectives. A series of NADES consisting of decanoic acid, menthol, thymol, and lidocaine as hydrogen bond acceptors/donors (HBAs/HBDs) were prepared, and the CO₂ solubility in them was determined experimentally. Perturbed-Chain Statistical Associating Fluid Theory has been first extended to simultaneously predict the thermodynamic properties (i.e., Henry's constants, enthalpy change, Gibbs free energy change and entropy change for CO₂ absorption in NADESs) as well as viscosity by combining with entropy scaling theory. Molecular insights into the structure–property relationship between different HBA/HBD structures and CO₂ solubility were revealed by quantum chemical calculations and molecular dynamics simulations. This work provides theoretical guidance for the development and screening of novel NADES for efficient CO capture.