Surface and Interface Engineering for Advanced Nanofiltration Membranes

Nanofiltration has been attracting great attention in alleviating the global water crisis because of its high efficiency, mild operation, and strong adaptability. Over decades, it remains a challenge to break the upper limit of performance and establish the formation-structure-property relationship for nanofiltration membranes. This feature article summarizes our recent progress in the preparation of high-performance thin-film composite (TFC) nanofiltration membranes, focusing on the mussel-inspired deposition method and the optimized interfacial polymerization (IP). By accelerating the oxidation of polydopamine and equilibrating the rate of aggregation and deposition processes, the mussel-inspired deposition method realizes the rapid and uniform formation of selective coatings or nanofilms. Diverse deposition systems endow the selective layer with rich chemical structures and easy post-functionalization, highlighting its potential in water treatment. As for optimizing the conventional IP, the rapid polycondensation of amine and acid chloride groups is slowed down to enable the controllability of IP at the water-organic interface. The homogeneity and integrity of the TFC membranes are improved by constructing a uniform reaction platform and introducing a viscous medium to control the amine diffusion, which facilitates the water permeability and promotes the separation efficiency. We have proposed a series of practical strategies for improving TFC membranes and might provide more inspiration for other nanofiltration techniques.