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Zhao Z, Di N, Zha Z, Wang J, Wang Z, Zhao S. Positively Charged Polyamine Nanofiltration Membrane for Precise Ion-Ion Separation. ACS Appl Mater Interfaces 2023; 15:48695-48704. [PMID: 37796665 DOI: 10.1021/acsami.3c11076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/07/2023]
Abstract
Positively charged nanofiltration (NF) membranes offer enormous potential for lithium-magnesium separation, hard water softening, and heavy metal removal. However, fundamental performance limitations for these applications exist in conventional polyamide-based NF membranes due to the negatively charged surface and low ion-ion selectivity. We hereby innovatively develop an advanced positively charged polyamine-based NF membrane built by the nucleophilic substitution of bromine and amine groups for precise ion-ion separation. Specifically, polyethylenimine (PEI) and 1,3,5-tris(bromomethyl)benzene (TBB) are interfacially polymerized to generate an amine-linked PEI-TBB selective layer with an ultrathin thickness of ∼95 nm, an effective pore size of 6.5 Å, and a strong positively charged surface with a zeta potential of +20.9 mV at pH 7. The PEI-TBB composite membrane achieves a water permeance of 4.2 L·m-2·h-1·bar-1, various divalent salt rejections above 90%, and separation factors above 15 for NaCl/MgCl2 and LiCl/MgCl2 mixed solutions. A three-stage NF process is implemented to achieve a Mg2+/Li+ mass ratio sharply decreasing from 50 to 0.11 with a total separation factor (SLi,Mg) of 455. Furthermore, the polyamine-based NF membrane exhibits excellent operational stability under continuous filtration and high operational pressure, demonstrating great application potential for precise ion-ion separation.
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Affiliation(s)
- Zhenyi Zhao
- School of Chemical Engineering and Technology, Tianjin University, Tianjin Key Laboratory of Membrane Science and Desalination Technology, State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, P. R. China
| | - Nanxi Di
- School of Chemical Engineering and Technology, Tianjin University, Tianjin Key Laboratory of Membrane Science and Desalination Technology, State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, P. R. China
| | - Zhiyuan Zha
- School of Chemical Engineering and Technology, Tianjin University, Tianjin Key Laboratory of Membrane Science and Desalination Technology, State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, P. R. China
| | - Jixiao Wang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin Key Laboratory of Membrane Science and Desalination Technology, State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, P. R. China
| | - Zhi Wang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin Key Laboratory of Membrane Science and Desalination Technology, State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, P. R. China
| | - Song Zhao
- School of Chemical Engineering and Technology, Tianjin University, Tianjin Key Laboratory of Membrane Science and Desalination Technology, State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, P. R. China
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