Preparation and performance of “three-layer sandwich” composite loose nanofiltration membrane based on mussel bionic technology

Abstract In this study, a novel “three-layer sandwich” composite loose nanofiltration (NF) membrane structure by mussel bionic technology was constructed on a porous polyvinylidene fluoride (PVDF) substrate membrane, with a mussel bionic coating as the middle layer and the complex network of polyphenols and metal ions as the top layer. The new composite NF membrane had comprehensive properties such as excellent separation performance, good hydrophilicity and strong antifouling ability. The experimental results showed that the combination of tannic acid (TA) and iron ion (Fe 3+ ) could significantly improve the comprehensive performance of the composite NF membrane, with water flux of more than 3000 L/(m 2 ∙h), and the retention rate of dyes and bovine serum protein (BSA) exceeded 90 %, and contact angle was up to 30°. The combination of TA and copper ion (Cu 2+ ) can greatly enhance the antifouling performance and interception ability of methylene blue. The complexation activity of metal ions and polyphenols was related to the oxidation of metal ions. The PVDF/DA-PEI/TA-M + composite structure scheme of “three-layer sandwich” NF membrane provides a new idea and future development direction for the development of novel NF membranes with excellent comprehensive performance.