With
the increasingly serious pollution of organic solvents, the
development of durable resistance of organic solvents and robust ion-exchange
membranes is of great significance for specific electrodialysis processes.
In this work, a series of resistant organic solvent cation-exchange
membranes (CEMs) have been prepared by using small and short Kevlar
nanofibers modified with the poly(4-styrene sulfonic acid-co-maleic acid) sodium salt and polyethyleneimine via amide condensation. The investigation demonstrates that
the as-prepared Kevlar nanofiber-based CEM (PP-K-5.0 CEM) exhibits
a high tensile strength of 142.23 MPa and good electrochemical performance.
To evaluate the stability of the desalination performance of the prepared
CEM in the organic solvent, the CEM was immersed in acetone and ethanol
aqueous solutions at room temperature for 7 d. As for the evaluation
of CEM performance, electrodialysis with treated CEM (PP-K-5.0 CEM)
can achieve high desalination efficiencies (84.5% in 90% ethanol solution
and 85.4% in 90% acetone solution) and concentration efficiencies
(90.7% in 90% ethanol solution and 87.5% in 90% acetone solution),
respectively. The results indicate that this work could provide a
design route for preparing robust CEMs, which is potentially applied
in desalination systems containing organic solvents.
Developing monovalent cation permselective membranes (MCPMs) with high-efficient permselectivity is the core concern in specific industrial applications. In this work, we have fabricated a series of novel cation exchange membranes (CEMs) based on sulfonated polysulfone (SPSF) surface modification by polyethyleneimine (PEI) and 4′-aminobenzo-12-crown-4 (12C4) codeposited with dopamine (DA) successively, which was followed by the cross-linking of glutaraldehyde (GA). The as-prepared membranes before and after modification were systematically characterized with regard to their structures as well as their physicochemical and electrochemical properties. Particularly, the codeposition sequence of modified ingredients was investigated on galvanostatic permselectivity to cations. The modified membrane (M-12C4-0.50-PEI) exhibits significantly prominent selectivity to Li+ ions (PMg2+Li+ = 5.23) and K+ ions (PMg2+K+ = 13.56) in Li+/Mg2+ and K+/Mg2+ systems in electrodialysis (ED), which is far superior to the pristine membrane (M-0, PMg2+Li+ = 0.46, PMg2+K+ = 1.23) at a constant current density of 5.0 mA·cm−2. It possibly arises from the synergistic effects of electrostatic repulsion (positively charged PEI), pore-size sieving (distribution of modified ingredients), and specific interaction effect (12C4 ~Li+). This facile strategy may provide new insights into developing selective CEMs in the separation of specific cations by ED.
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