Green and large-scale production of covalent organic framework nanofiltration membranes

Covalent organic frameworks (COFs) are porous, crystalline materials formed through the covalent bonding of organic units. They are characterized by high surface areas and tunable pore sizes, making them promising candidates for membrane separation. Typically, COFs have pore sizes ranging from 1 to 3 nm, which is ideal for nanofiltration applications. Over the last decade, COF membranes (COFMs) have rapidly advanced and demonstrate significant potential in nanofiltration. However, challenges remain in achieving environmentally friendly and scalable fabrication. This Review addresses the key challenges and opportunities for green and large-scale production of COFMs. We critically evaluate the advantages and disadvantages of various laboratory fabrication methods and propose strategies for eco-friendly and scalable preparation, focusing on green solvents, large-area production, and production efficiency. Finally, we offer our perspectives on synthesizing COFMs sustainably at large-scale. Covalent organic frameworks are ideal materials as nanofiltration membranes for pharmaceuticals, hormones, antibiotics, and pesticide separation. This Review covers the challenges and solutions to green and sustainable large-scale fabrication of covalent organic framework membranes.