ZIF-8 or Zn/Co-ZIF Filled PIM-1 Mixed Matrix Membranes for Separation of Ethanol and Butanol from Aqueous Solution via Pervaporation

Abstract

Membranes with the promising abilities in application of ethanol and butanol removal from fermentation broth are essentially required. Therefore, in this study, hydrophobic mixed matrix membranes (MMMs) were synthesized with Polymer: of Intrinsic Microporosity (PIM-1) and two types of Zeolitic Imidazole Frameworks; ZIF-8 and a composite Zn/Co-ZIF. The prepared ZIF fillers and MMMs were analyzed by XRD, FTIR, SEM and contact angle measurements. The synthesized membranes were analyzed for their separation performance of two binary mixes made of ethanol/water and butanol/water comprising 5wt% alcohol, via pervaporation. Separation performances of membranes indicate that all membranes show higher separation factor for butanol as compared to ethanol. Moreover, PIM-1/Zn/Co-ZIF 20wt% membranes showed 129% higher separation in comparison with pristine PIM-1 membranes. PIM-1/ZIF-8 20wt% membrane showed highest flux of 139 kg µm/m2h. Comparison of results shows that PIM-1/ZIF-8 MMMs give better performances in terms of high fluxes, whereas PIM-1/Zn/Co-ZIF MMMs give better membrane performance by giving high separation factors. Water contact angle measurements of membranes indicate hydrophobic nature of PIM-1/Zn/Co-ZIF of 104.7 membranes. The flux increases with increasing filler loading which ensures the formation of defect free membranes without presence of any filler agglomerates. The enhanced separation factor of Zn/Co-ZIF makes it attractive filler in membrane separation techniques.