Solvent stable thin-film composite membranes with a COF interlayer for artemisinin enrichment

Organic solvent nanofiltration (OSN) is an energy-efficient method for pharmaceutical separation that preserves bioactivity while enabling solvent recycling. Polyamide (PA) thin-film composite (TFC) membranes have demonstrated great potential for this application because of their easy fabrication, robust stability in solvents, and excellent separation performance. However, achieving controllable interfacial polymerization (IP) of the PA layer on a solvent-resistant support remains a challenge. To address this issue, a sulfonated COF-Na + interlayer was developed and deposited onto nylon, providing a smooth and uniform surface that facilitates the formation of a continuous and defect-free PA layer. The resulting membrane exhibited a high methanol permeance of 9.95 L m -2 h -1 bar -1 with excellent rejection above 94% for both charged and uncharged molecules. This approach was successfully applied to both organic and inorganic microfiltration substrates, demonstrating that this COF interlayer effectively eliminates variations in support materials by providing a uniform and smooth surface for the IP process. In this work, the resulting membrane demonstrated over 98% artemisinin rejection in ethanol, making it highly efficient for concentrating artemisinin while simultaneously recycling ethanol, thereby reducing energy consumption and minimizing solvent waste. • PA TFC membranes were fabricated on both polymeric and ceramic substrates. • A COF-H + interlayer was converted to COF-Na + to aid in PA formation. • The PA TFC membranes showed high dye rejection in organic solvents. • The membranes enabled efficient artemisinin enrichment.