Supramolecular chemistry assisted construction of ultra-permselective polyamide nanofilm with asymmetric structure for ion sieving

• Published in: Desalination Vol. 568; p. 117029
• Main Authors: Hu, Ping, Song, Haojie, Xu, Zewen, Jia, Chaozheng, Wang, Ning, Yuan, Bingbing, Niu, Q. Jason
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.12.2023
• Subjects: Asymmetric PA nanofilm; Interfacial polymerization; Ion sieving; Spatial-temporal regulation; Supramolecular chemistry; Interfacial polymerization; Spatial-temporal regulation; Asymmetric PA nanofilm; Supramolecular chemistry; Ion sieving
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2023.117029

Highly-permselective NF membranes are critical to energy-efficient ionic separation. Herein, an ultra-permselective polyamide (PA) nanofilm with asymmetric two-layered structure is achieved by supramolecular chemistry modulated interfacial polymerization (IP) process. Such nearly-40-nm asymmetric PA nanofilm consists of a PA dense layer with nanoscale homogeneity and a polydopamine-β-cyclodextrin (PDA-β-CD) porous layer induced by mussel-inspired surface chemistry, with crosslinking. Experimental characterizations reveal that the exceptionally-hydrophilic and highly-porous PDA-β-CD coating imparts the spatial enrichment and temporal retardation of amine monomers via H-bonding and host-guest interactions, conducing to form the diffusion-difference-enabled striped PA nanofilm with nanoscale ordered structures and enhanced cross-linking degree. Meanwhile, the PDA-β-CD porous coating not only can finely tune the microstructure of PA nanofilm, but also highly prefers for surmounting funnel effect and shortening water transport path. As a result, the resultant asymmetric PA nanofilm attains a noticeable water permeance of 38.59 ± 2.42 L m−2 h−1 bar−1, competitive retention of Na2SO4 (99.4 ± 0.2 %) and unprecedented Cl−/SO42− selectivity of 202.1, far outperforming the state-of-the-art commercial and lab-made NF membranes. Moreover, it evinces an outstanding ion-sieving performance under the high-salinity solutions, suggesting that our approach for tuning microstructure enables the development of ultra-permeability and excellent selectivity for application in brine refinement and salt reclamation. •Supramolecular chemistry modulated IP process was proposed.•The PA nanofilm with nanoscale homogeneity and asymmetric structure was engineered.•PDA-β-CD coating induced spatial enrichment and temporal retardation of PIP monomers.•The asymmetric PA nanofilm evinced an outstanding ion sieving performance.