Facile fabrication of chlorine resistance Amd/TA-PVA/Amn COF composite membrane via multi-interfacial polymerization toward dye sieving

Covalent organic framework (COF) membranes have garnered significant attention as a promising separation technology for dye wastewater treatment, owing to their meticulously ordered pore structure and exceptional chemical stability. The Polyamide COF (Amd-COF) membrane, characterized by amide-linkages, exhibits excellent hydrophilicity and chemical stability, whereas the polyamine COF (Amn-COF) membrane, featuring amine-linkages, demonstrates remarkable flexibility and resistance to chlorine. In this study, we present the synthesis of defect-free Amd/TA-PVA/Amn COF composite membranes with large area and continuous structure through multi-interfacial polymerization. The incorporation of an intermediate layer (TA-PVA) enables stable formation of strong hydrogen bonds between Amd-COF and Amn-COF, thereby enhancing the durability of the composite membranes. Due to the unique structural features and functional groups of the Amd/TA-PVA/Amn COF composite membranes, they exhibit not only high water permeability (119.24 L•m −2 h −1 bar −1 ) but also exceptional rejection efficiency towards Rhodamine B, achieving up to 96.55 % removal. Specifically, the membranes treated with a chlorination intensity of 2000 ppm exhibit stable permeance and dye rejection performance. Moreover, these membranes exhibit exceptional stability in both structure and performance over multiple cycles. This can primarily be attributed to the highest density of amino moieties and phenolic hydroxyl groups on their surface. This work underscores the significant potential of COF membrane incorporating amide and amine functionalities for high-performance separation and anti-chlorine applications.