Regulating interfacial polymerization via constructed 2D metal-organic framework interlayers for fabricating nanofiltration membranes with enhanced performance

Abstract

Interlayered thin-film nanocomposite (TFN) membranes have been proven to achieve enhanced water permeance for desalination applications, while those lacking effective control over the construction of interlayers were prone to unsatisfactory permselectivity. In this study, a high-performance TFN membrane was constructed via interfacial polymerization on a Metal-Organic Frameworks (MOFs)-interlayered polyethersulfone substrate. Regulating the thickness of the MOFs (copper-tetrakis(4-carboxyphenyl) porphyrin, Cu-TCPP) interlayer could effectively tailor the structural parameters (effective filtration area, selective layer thickness, and pore size) and physicochemical properties of the membrane. A resistance-in-series model was applied to analyze the hydraulic resistance distribution and the specific value of the intrinsic solution permeability of each layer of the TFN membranes. Results showed that the interlayer with a proper deposition density of MOFs nanosheets could simultaneously increase the cross-linking degree by adsorbing the PIP monomers and reduce the thickness of the PA layer to enhance the intrinsic permeability. The optimal membrane with a thin PA film (20 nm) displayed an excellent water permeance of 32.7 L·m−2·h−1·bar−1 and an ultrahigh NaCl/Na2SO4 selectivity of 271.7. Moreover, the membrane demonstrated remarkable stability during 120 h filtration. This work provides a promising strategy for fabricating TFN membranes with higher selectivity and enhanced comprehensive performance.