Asymmetric polyamide nanofilms with highly ordered nanovoids for water purification

• Published in: Nature communications 2020-11, Vol.11 (1), p.6102-6102, Article 6102
• Main Authors: Yuan, Bingbing, Zhao, Shengchao, Hu, Ping, Cui, Jiabao, Niu, Q. Jason
• Format: Article
• Language: English
• Subjects: 132/122; 140/131; 140/146; 147/135; 147/143; 147/3; 639/301/923/1028; 639/638/455/956; 639/638/455/957; Asymmetry; Humanities and Social Sciences; Membrane permeability; Membranes; Morphology; multidisciplinary; Nanofiltration; Nanotechnology; Permeability; Pervaporation; Polyamide resins; Polyamides; Polysulfone; Polysulfone resins; Rejection rate; Reverse osmosis; Salt rejection; Science; Science (multidisciplinary); Selectivity; Upper bounds; Water purification
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-19809-3

Tailor-made structure and morphology are critical to the highly permeable and selective polyamide membranes used for water purification. Here we report an asymmetric polyamide nanofilm having a two-layer structure, in which the lower is a spherical polyamide dendrimer porous layer, and the upper is a polyamide dense layer with highly ordered nanovoids structure. The dendrimer porous layer was covalently assembled in situ on the surface of the polysulfone (PSF) support by a diazotization-coupling reaction, and then the asymmetric polyamide nanofilm with highly ordered hollow nanostrips structure was formed by interfacial polymerization (IP) thereon. Tuning the number of the spherical dendrimer porous layers and IP time enabled control of the nanostrips morphology in the polyamide nanofilm. The asymmetric polyamide membrane exhibits a water flux of 3.7−4.3 times that of the traditional monolayer polyamide membrane, showing an improved divalent salt rejection rate (more than 99%), which thus surpasses the upper bound line of the permeability−selectivity performance of the existing various structural polyamide membranes. We estimate that this work might inspire the preparation of highly permeable and selective reverse osmosis (RO), organic solvent nanofiltration (OSNF) and pervaporation (PV) membranes. Structure and morphology are critical to the performance of permeable and selective polyamide membranes in water purification. Here, the authors report a two layer asymmetric polyamide nanofilm in which a spherical polyamide dendrimer porous lower and a polyamide dense upper layer form hierarchical nanovoids.