A large-area MOF-based membrane for challenging CO₂ purification and ethanol/CO₂/N₂ ternary mixture separation

Bioethanol has garnered widespread attention as a potential substitute for traditional fossil fuels. Focusing on the treatment of bioethanol fermentation exhaust is crucial for optimizing bioethanol recovery and achieving carbon dioxide (CO₂) purification. This study successfully achieved the large-scale synthesis of zeolitic imidazolate framework-8 (LSZIF-8), which was then incorporated into polydimethylsiloxane (PDMS) to fabricate large-area ZIF-8/PDMS/PVDF mixed matrix membranes (MMMs) for bioethanol recovery from fermentation exhaust via vapor permeation (VP) processes. The ZIF-8/PDMS/PVDF MMMs exhibited a 1.5-time increase in ethanol permeability and selectivity improved by 1.7 times compared to the PDMS/PVDF membrane. The mass transport behavior of ethanol and CO₂ molecules within the membrane, as well as examining the interactions between different components was systematically explored. It delves into the disparities in separation performance between PDMS/PVDF membrane and ZIF-8/PDMS/PVDF MMMs with nitrogen (N₂), water vapor as the third component. Notably, high-quality LSZIF-8 crystals serves as a crucial source of raw materials for the continuous preparation of high-performance MMMs, addressing the limitation of traditional nanoparticle fillers in terms of scalability for production. This study paving new avenues for purifying fermentation exhaust and recovering bioethanol, while simultaneously present significant potential for industrial applications.