Performance evaluation of vacuum-assisted CO2 desorption from ionic liquids using hollow-fiber membrane contactors

This study combines computational fluid dynamics (CFD) modeling with experimental data to investigate CO 2 desorption from ionic liquids (ILs) using a polypropylene hollow-fiber membrane contactor (HFMC) operated under vacuum conditions. Two imidazolium-based ILs, [emim][Ac] and [emim][EtSO 4 ], were evaluated as CO 2 -rich solvents during laboratory-scale regeneration. Model validation was performed at 289 K and 0.04 bar, showing very good agreement with the experimental CO 2 loading and desorption flux profiles for both ILs. The final predicted desorption efficiencies were 58.3% for [emim][Ac] and 15.7% for [emim][EtSO 4 ], with high R 2 values of 0.974 and 0.996, and RMSE values of 5.540 × 10 -3 and 9.891 × 10 -6 for [emim][Ac] and [emim][EtSO 4 ], respectively. Sensitivity analysis showed that temperature, vacuum pressure, and fiber area strongly affect the regeneration process. Increasing the temperature improved CO 2 desorption by reducing IL viscosity, enhancing mass transfer, and decreasing CO 2 solubility, while stronger vacuum conditions increased the desorption driving force. For [emim][Ac], the desorption efficiency increased from about 60.1% at 289 K to almost 94% at 389 K under a vacuum pressure of 0.035 bar. Increasing the number of hollow fibers also improved performance by increasing the available gas-liquid contact area, with efficiencies close to 90 – 95% achieved under favorable operating conditions. Overall, the close agreement between the CFD predictions and experimental data confirms that the model can reliably describe IL regeneration under the validated conditions. Furthermore, the sensitivity simulations at higher temperature and different pressures provide valuable model-based insights into expected performance trends and the optimization potential of HFMC-based IL regeneration.