Coordinate covalent grafted ILs-modified MIL-101/PEBA membrane for pervaporation: Adsorption simulation and separation characteristics

High porosity and large pore volume of MIL-101 MOF makes it a potential material to be used in membrane separation technology. However, the extra-large pore size and natural hydrophilicity restrict its application in the organic perm-selective pervaporation process. To overcome this issue, Herein, we successfully synthesized ILs@MOFs composite by modifying MIL-101 via coordinative covalent grafting of designed hydrophobic ionic liquids (ILs). Later on, synthesized ILs-modified MIL-101 was embedded into poly (ether-block-amide) (PEBA) polymer to fabricate mixed matrix membranes (MMMs) for ethyl acetate perm-selective pervaporation. Incorporation of ILs within the cages and over the surface of MIL-101 not only successfully tuned the pore structure and surface properties of MIL-101 but also inhibits the formation larger aggregates with no obvious defects in resultant MMMs. Moreover, molecular simulation verified that the grafted ILs endowed MIL-101 with better adsorption ability for ethyl acetate and improved interfacial compatibility with PEBA. The optimized MMMs exhibited outstanding separation performance for 5 wt% feed solution at 30 degrees C, with a separation factor of 207.6 and normalized total flux of 51.8 kg.mu m.m(-2).h(-1). Compared with the pure PEBA membrane, the separation factor and ethyl acetate flux increased by 205.7% and 129.5%, respectively, while the MMMs embedding original MIL-101 showed a decrease in separation factor. This study may inspire the design and construction of highperformance MMMs by employing modification in porous nanomaterial microstructure.

Automated summary

High porosity and large pore volume of MIL-101 MOF make it a potential material for membrane separation technology. By incorporating ILs within the cages and over the surface of MIL-101, the pore structure and surface properties were successfully tuned, leading to outstanding separation performance in mixed matrix membranes (MMMs). This study may inspire the design of high-performance MMMs by modifying porous nanomaterial microstructure.