Ionic COF Composite Membranes for Selective Perfluoroalkyl Substances Separation.

High-performance membranes are critical to membrane separation technology. In recent years, 2D covalent organic frameworks (2D COFs) have attracted extensive attention in the field of membrane separation due to their high porosity, ordered channels, and fine-tuned pore sizes, which are considered as excellent candidate to solve the trade-off between membrane selectivity and permeability. Herein, two kinds of ionic 2D COFs with different charge properties (termed as iCOFs) are integrated into polyacrylonitrile (PAN) substrates to form two composite membranes (PAN@iCOFs) with excellent selective perfluoroalkyl substances (PFASs) separation performance with high solvent permeability and good mechanical properties. The as-prepared PAN@iCOFs composite membranes can selectively reject more than 99.0% of positively and negatively charged PFASs in wastewater while maintaining good stability and recyclability.