Improving Gas Separation Performance of Poly(vinylidene fluoride) Based Mixed Matrix Membranes Containing Metal–Organic Frameworks by Chemical Modification

In this study, poly(vinylidene fluoride) (PVDF) was modified by a mixture of KOH and KMNO4 in order to effect HF elimination. During this reaction, some functional groups were created in the PVDF structure. The metal–organic frameworks, MIL-53(Al) and NH2-MIL-35(Al), were embedded in modified PVDF (M-PVDF) to fabricate mixed matrix membranes (MMMs). Different characterization techniques such as FT-IR, XRD, SEM, DSC, TGA, and contact angle tests have been implemented to identify the prepared membranes. Pure and mixed (1:1) CO2 and CH4 were used to test gas separation performance of MMMs. CO2 permeance was increased for pure M-PVDF membrane compared with the pristine PVDF by 31.2%. Upon 10 wt % loading of MIL-53(Al) and NH2-MIL-35(Al) in M-PVDF, CO2 permeability increased 104.33% and 80.02% relative to the unfilled M-PVDF. The highest CO2/CH4 ideal selectivity and separation factor of 43.9 and 42.65, respectively, were reported for NH2-MIL-35(Al)/M-PVDF with 10 wt % loading. These improvements could be attributed to the breathing effect of MOFs, created polar moieties in PVDF through the modification, and hydrogen bonding interactions between the MOFs and the polymer.