Deep Separation of the Methyl Ethyl Ketone/ sec -Butyl Alcohol/Water Azeotropic System: Molecular Mechanistic Insights and Multienergy-Saving Process Intensification

To address the challenging separation of industrial wastewater containing methyl ethyl ketone (MEK) and sec-butyl alcohol (SBA), this study proposes a multiscale synergistic intensification scheme. First, entrainers were systematically screened using vapor–liquid equilibrium (y-x) phase diagrams and the COSMO-SAC model. Subsequently, density functional theory calculations and molecular dynamics simulations were combined to deeply analyze the microscopic intermolecular interactions, thereby elucidating the separation mechanism of the extractive distillation process (EDP). Guided by this molecular mechanism, the corresponding intensified process was developed. To further reduce energy consumption, five energy-saving intensified configurations were designed by integrating four energy-saving technologies: natural decantation (ND), dividing-wall column (DWC), heat pump (HP), and intermediate reboiler (IR). Global parameter optimization was subsequently accomplished using a genetic algorithm. Comprehensive process evaluations, including economic metrics, energy consumption, acid gas emissions, and thermodynamic efficiency, were conducted for all configurations. The holistic assessment demonstrates that the IR-HP-DWC-ND-EDP achieves the best overall performance: compared with the conventional EDP, its total annual cost is reduced by 20.82%, both total energy consumption and acid gas emissions are cut by 33.25%, and thermodynamic efficiency is boosted by 67.07%. This process successfully achieves low-carbon, highly efficient separation and high-value resource recovery from MEK/SBA industrial wastewater.