Polycrystalline Iron(III) metal-organic framework membranes for organic solvent nanofiltration with high permeance

There is an urgent demand for separation membranes based on metal-organic frameworks (MOFs) with high efficiency, low waste generation, and low energy consumption. Herein, we report the fabrication of high-quality, continuous iron (III)-based PCN-250 polycrystalline MOF membranes for organic solvent nanofiltration. Due to the usage of rub seeding, the PCN-250 membrane has a small thickness of 3.7 μm and exhibits pure solvent permeance as high as 337.9 L m−2 h−1 bar−1 for methanol, 69.2 L m−2 h−1 bar−1 for ethanol, and 17.2 L m−2 h−1 bar−1 for N-methyl-2-pyrrolidone (NMP). The membrane has pore sizes ranging from 0.6 to 1.0 nm, with a molecular weight cut-off of ca. 1300 g/mol. In addition, it exhibits excellent molecular separation performance (methyl blue rejection of 93.7%) alongside a high NMP permeance of 2.6 L m−2 h−1 bar−1. Moreover, our study confirms that the PCN-250 MOF membrane has good water, acid, and organic solvent resistance. This remarkable separation performance, combined with the outstanding stability in water, acid, and organic solvents, makes the PCN-250 membrane a promising candidate for organic solvent nanofiltration.