Polyamide membranes with nanoscale ordered structures for fast permeation and highly selective ion-ion separation

• Published in: Nature communications Vol. 14; no. 1; p. 1112
• Main Authors: Zhao, Changwei, Zhang, Yanjun, Jia, Yuewen, Li, Bojun, Tang, Wenjing, Shang, Chuning, Mo, Rui, Li, Pei, Liu, Shaomin, Zhang, Sui
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 27-02-2023; Nature Publishing Group; Nature Portfolio
• Subjects: 639/166/898; 639/301/357/537; 704/172/169/896; Carbon nitride; Chlorides; Computational fluid dynamics; Computer applications; Desalination; Diffusion rate; Dynamic structural analysis; Fluid dynamics; Hexanes; Humanities and Social Sciences; Hydrodynamics; Membrane permeability; Membranes; Molecular dynamics; multidisciplinary; Nanofiltration; Nanotechnology; Permeation; Piperazine; Polyamide resins; Polyamides; Polymerization; Rejection; Science; Science (multidisciplinary); Selectivity; Separation; Sodium sulfate; Water purification; Water treatment
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-36848-8

Fast permeation and effective solute-solute separation provide the opportunities for sustainable water treatment, but they are hindered by ineffective membranes. We present here the construction of a nanofiltration membrane with fast permeation, high rejection, and precise Cl
-
/SO
4
2-
separation by spatial and temporal control of interfacial polymerization via graphitic carbon nitride (g-C
3
N
4
). The g-C
3
N
4
nanosheet binds preferentially with piperazine and tiles the water-hexane interface as revealed by molecular dynamics studies, thus lowering the diffusion rate of PIP by one order of magnitude and restricting its diffusion pathways towards the hexane phase. As a result, membranes with nanoscale ordered hollow structure are created. Transport mechanism across the structure is clarified using computational fluid dynamics simulation. Increased surface area, lower thickness, and a hollow ordered structure are identified as the key contributors to the water permeance of 105 L m
2
·h
−1
·bar
−1
with a Na
2
SO
4
rejection of 99.4% and a Cl
-
/SO
4
2-
selectivity of 130, which is superior to state-of-the-art NF membranes. Our approach for tuning the membrane microstructure enables the development of ultra-permeability and excellent selectivity for ion-ion separation, water purification, desalination, and organics removal.
Membranes with precise ion-ion separation are critical for sustainable water treatment. Here, authors demonstrated controlled construction of a nanofiltration membrane with fast permeation and high Cl
-
/SO
4
2-
selectivity by simultaneous spatial and temporal control of interfacial polymerization.