Electrostatic assembly-derived β-ketoenamine covalent organic framework/polyacrylonitrile composite nanofiltration membrane for efficient removal of emerging contaminants

Emerging contaminants (ECs) such as pharmaceuticals pose increasing threats to aquatic environments and human health. Therefore, it is urgent to develop high-performance nanofiltration (NF) membranes for the efficient removal of ECs. In this work, we present a scalable and energy-efficient strategy for fabricating a novel covalent organic framework (COF)-based NF membrane under mild conditions. The membrane was prepared via electrospinning and subsequent electrostatic assembly, consisting of a porous PAN@TpPa support layer and a precisely deposited TpPa-SO 3 H selective layer. We employed a key interfacial engineering approach, in which protonated TpPa interlayer enhanced electrostatic interactions between layers, thereby forming a dense and negatively charged interface with outstanding long-term stability. The optimized membrane with 72 h TpPa growth time and 30 mg TpPa-SO 3 H loading, achieved a high rejection of 98.89 % for diclofenac sodium (DS) and an excellent permeance of 16.79 L m −2  h −1 ·bar −1 , outperforming commercial NF membranes. Moreover, the PAN@TpPa/TpPa-SO 3 H composite membrane exhibited remarkable long-term stability and superior antifouling performance. Molecular dynamics simulations revealed that the superior separation performance results from the synergistic effects of size sieving and Donnan exclusion. This work provides a mild and scalable interfacial engineering strategy for developing COF-based NF membranes, demonstrating great potential for the effective removal of ECs from wastewater.