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

Abstract

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 °C, with a separation factor of 207.6 and normalized total flux of 51.8 kg·μm·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 high-performance MMMs by employing modification in porous nanomaterial microstructure.