Thin film composite nanofiltration membrane with nanocluster structure mediated by graphene oxide/metal-polyphenol nanonetwork scaffold interlayer

In this study, novel thin film composite (TFC) nanofiltration membrane with nanocluster structure was successfully synthesized by confining interfacial polymerization (IP) on graphene oxide/metal-polyphenol (GO/TA-Mn+) nanonetwork scaffold interlayer for the first time. By metal-polyphenol network coordination cross-linking, very stable GO/TA-Mn + nanonetwork scaffold was constructed via brush coating, which well-regulated the pore structure and distribution of the substrate, greatly restricting the invasion of polyamide (PA) matrix to the pore of substrate. Moreover, the GO/TA-Mn + modified substrate effectively mediated the amine monomers diffusion during interfacial polymerization, contributing to form an ultrathin PA layer (∼19.2 nm) with nanocluster structure. The separation performance therefore can feasibly be tuned by the metal ions of different valence states. The strategy also gives appropriate level of generality for synthesis of versatile defect-free TFC membranes on various substrates. The prepared TFC-GO/TA-Al3+ membrane held outstanding separation performance with water permeability of 16.87 L m−2 h−1 bar−1 and competitive rejection of 97.2% for Na2SO4, displaying the permeability increment of about 4.5 times without sacrificing salt rejection.