Mechanistic Investigation and Process Simulation of Liquid–Liquid Extraction of Pyridine-Based Pollutants from Aqueous Solutions Using Hydrophobic Deep Eutectic Solvents

To address the treatment of chemical wastewater containing the highly toxic and recalcitrant 2,4,6-trimethylpyridine (Col), this study evaluates the potential of hydrophobic deep eutectic solvents (HDESs) for Col removal via liquid–liquid extraction (LLE). thymol-decanoic acid (Thy-Dec) was selected as the optimal extractant via COSMO-RS and compared with methyl isobutyl ketone (MIBK) using multiscale simulations. Quantum chemical (QC) calculations revealed that Thy-Dec exhibits high selectivity due to its strong hydrogen-bond donor ability and electrostatic complementarity with Col. Molecular dynamics (MD) simulations dynamically elucidated the mass transfer behavior of Col across phases during LLE. An extraction-distillation integrated process modeled in Aspen Plus demonstrated that the Thy-Dec system outperforms MIBK in both environmental and economic performance, providing a theoretical basis for HDES-based recovery of pyridine compounds from aqueous streams.