Grape seed oligomeric proanthocyanidins-assembled membranes with a highly negatively charged surface for high-performance nanofiltration

• Grape seed oligomeric proanthocyanidins was used to prepare NF membrane. • OPC-based membrane has a loose structure with a large free volume. • OPC endowed the membrane with an ultra-highly negatively charged surface. • OPC-based TFC membranes have excellent permeate flux and rejection against Na 2 SO 4. Recently, it is crucial to develop a new synthetic membrane with a superior permeability and rejection for reduction energy consumption and miniaturization equipment. Herein, a novel thin film composite (TFC) nanofiltration (NF) membranes, were fabricated successfully with natural grape seed oligomeric proanthocyanidins (OPC) by means of using 1,3,5-trimesoyl chloride as bridging molecules via a facile interfacial polymerization. Given the abundance of phenolic hydroxyl groups on OPC molecules, the unreacted ones should be reserved concomitantly to endow the membrane with a strong internal polarity. As expected, the obtained OPC-based TFC membranes had a large free volume that confirmed by molecular dynamics simulation and accessory analysis, which facilitated the water molecules infiltration into the matrix of membranes. In addition, the strong polarity of phenolic hydroxyl endowed the membrane with a highly negatively charged surface that could enhance the Donna exclusive effect against anions. The resultant OPC-based membranes exhibited an ultrahigh water permeance of 37.5 L·m −2 ·h −1 ·bar −1 with a satisfactory rejection against Na 2 SO 4 (98.7%). Simultaneously, the inherent oxygen functional groups of OPC with excellent hydrophilicity endowed the OPC-based membranes with an outstanding antifouling property. Furthermore, the membrane performed excellent anti-bacterial activity, owing to the effect of OPC with protein. In summary, the proposed innovation strategy of using OPC to fabricate high-performance NF membranes really has a competitive advantage.