Capturing VOCs in the pharmaceutical industry with ionic liquids

• Published in: Chemical engineering science 2022-04, Vol.252, p.117504, Article 117504
• Main Authors: Gui, Chengmin, Li, Guoxuan, Zhu, Ruisong, Lei, Zhigang, Dong, Yichun
• Format: Article
• Language: English
• Subjects: Absorption; Ionic liquids; Quantum chemical calculation; Volatile organic compounds
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/j.ces.2022.117504

•[EMIM][Ac] was proposed to absorb ethanol and dichloromethane from waste gas.•UNIFAC-Lei model was well extended for predicting VLE of VOCs-IL systems.•The high VOCs removal ratio was verified by the absorption experiment.•The separation mechanism was explored by various quantum chemical calculations. 1-ethyl-3-methylimidazolium acetate ([EMIM][Ac]) was adopted to absorb two common pharmaceutical volatile organic compounds (VOCs), dichloromethane (DCM) and ethanol. The vapor–liquid equilibrium experimental data of the VOC-ionic liquid (IL) systems were measured. The absorption experiment was carried out at 20 °C and at ambient pressure, with a gas flow rate of 1 L/min and an absorbent flow rate of 20 mL/min. The results showed that the removal ratios of DCM and ethanol reached 91.82% and 97.01%, respectively. Furthermore, the mechanism of IL capturing DCM and ethanol was systematically studied using the COSMO-RS model and a quantum chemical calculation. The results demonstrated that the separation capability of [EMIM][Ac] mainly depended on the strong [Ac]−-VOC interaction. Finally, industrial-scale VOC capture processes were established and optimized. The results showed that IL process achieved a lower total heat duty and a higher increase in green degree compared with triethylene glycol process.