New strategy for structure rearrangement of thin-film composite (TFC) polyamide (PA) membranes and offering potential use in both aqueous and organic solvents

• Published in: Journal of membrane science Vol. 704; p. 122888
• Main Authors: Xu, Sun-Jie, Li, Hua-Xiang, Luo, Li-Han, Yan, Hong-Fei, Li, Hong-Bo, Jia, Rui, Tong, Yi-Hao, Han, Rui, Xu, Zhen-Liang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2024
• Subjects: Organic solvent nanofiltration (OSN); Sodium-ion battery electrolyte (SIBs) recycling; Structure rearrangement process (SRP); Thin-film composite (TFC); Thin-film composite (TFC); Structure rearrangement process (SRP); Sodium-ion battery electrolyte (SIBs) recycling; Organic solvent nanofiltration (OSN)
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2024.122888

The purity of sodium hexafluorophosphate (NaPF6) is crucial for the preparation of electrolytes in manufacturing. We propose a simple process in order to induce membrane structure rearrangement process (SRP) by activating thin-film composite (TFC) membranes with polyamide (PA) structure and explore their potential green recycling application in concentrating sodium-ion batteries (SIBs) electrolyte. The method utilizes a solution containing polar aprotic solvent as the soaking and activating solution to swell and disintegrate the loosely cross-linked PA layer, and a non-solvent solidification solution complete the SRP, enhancing the permeability of the PA layer while maintaining high rejection rates for divalent ions. Subsequently, during the further treatment of the membrane surface in structure rearrangement, tert-butanol (TBA) is introduced into the aqueous solution to reconstruct the surface PA layer, further improving the permeability. The optimal D8010T10 achieved a permeation flux of 24.2 L m−2 h−1·bar−1, with rejection rates for sodium sulfate (Na2SO4), magnesium chloride (MgCl2), and magnesium sulfate (MgSO4) reaching 94.7 %, 98.4 %, and 99.1 % respectively. And the mechanism of SRP with different solvent is analyzed and explained through dissipative particle dynamics (DPD) simulations. This study provides a commercially viable approach for manufacturing high-performance membranes. The D8010T10 membrane achieves more than 90 % separation efficiency for sodium hexafluorophosphate (NaPF6) dissolved in different solvents, providing a potential solution for the concentration and recovery of NaPF6 in lab-scale, verified its potential use in the organic solvent nanofiltration (OSN) and a path way for waste membrane recycling and degrading use in the industry. [Display omitted] •Structure rearrangement process (SRP) with soaking and solidification step was raised.•Tert-Butanol was screened to be the best solidification solvent among candidates.•Dissipative particle dynamics (DPD) simulations verified the SRP method.•The performance for recovering and producing NaPF6 was validated in lab-scale.•SRP offered a path way for waste membrane recycling and degrading use.