Ionic covalent organic frameworks (COFs) hold great promise in regulating the structure of polyamide nanofiltration membranes for divalent ions removal. In this work, we demonstrate cationic COF (cCOF) nanosheets engineered polyamide membrane with excellent divalent cations rejection. cCOF nanosheets as versatile regulator and an interlayer accelerate the self-sealing and self-termination of interfacial polymerization between polyethyleneimine and trimesoyl chloride, endowing membranes with dense network and small thickness. Meanwhile, the quaternary ammonium groups on cCOF nanosheets increase positive charges on membranes. Through synergistic intensification of electrostatic repulsion and size sieving, the resulting cCOF-PA membranes display excellent rejection for divalent cations (MgCl₂, 99.3%), superior to most reported polyethyleneimine-based polyamide membranes. This work highlights the significance of ionic COF materials in developing positively charged membranes for efficient ionic and molecular separations.

离子共价有机骨架（COF）在调节聚酰胺纳滤膜结构以去除二价离子方面具有广阔的前景。在这项工作中，我们展示了阳离子 COF (cCOF) 纳米片工程聚酰胺膜，具有出色的二价阳​​离子排斥能力。cCOF纳米片作为多功能调节剂和中间层加速了界面聚合的自密封和自终止聚乙烯亚胺和均苯三甲酰氯使膜网络致密、厚度小。同时，cCOF 纳米片上的季铵基团增加了膜上的正电荷。_{通过静电斥力和尺寸筛分的协同增强，所得的 cCOF-PA 膜对二价阳离子（MgCl 2} ，99.3％）表现出优异的排斥性，优于大多数报道的基于聚乙烯亚胺的聚酰胺膜。这项工作强调了离子 COF 材料在开发带正电膜以实现高效离子和分子分离方面的重要性。