Cross-linked anion-exchange membrane with side-chain grafted multi-cationic spacer for electrodialysis: Imparting dual anti-fouling and anti-bacterial characteristics

Polyimide (SPI) was functionalized using dianhydride with a high electron density in the carbonyl carbon atoms, and on active-sites (2,4,6-tris(dimethylaminomethyl) phenol: TAP) multi-cationic groups were grafted. Further, we fabricated multi-cationic cross-linked anion-exchange membrane (AEM) with tuneable polymer design by varying number of carbon chain in cross-linker spacer. CrQSPI@3 AEM with C3 spacer, exhibited 2.85 meq/g ion-exchange capacity, 21.4% water uptake, 20.7% swelling ratio, 13.87 x 10(-2) S/cm membrane conductivity, and assessed as optimized membrane for further experimental analysis. Architectural strategy including cross -linking, and side chain grafting of multi-cationic groups provides fine control over properties, stabilities, hydrophilic-hydrophobic characteristics, anti-fouling and anti-bacterial nature. Anti-fouling nature of CrQSPI@3 AEM were gaged by impedance spectroscopy, chronopotentiometry, and electrodialysis experiments, while anti-bacterial nature was studied against water borne Escherichia coli (E. coli). High electro-dialytic performance of CrQSPI@3 AEM (current efficiency: 97.4%, and energy consumption: 0.92 kW h/kg of NaCl removed) along with better stabilities, anti-fouling and anti-bacterial properties, revealed its suitability for water desalination and other diversified electrochemical applications. Described method provides facile membrane fabrication with superior performance to obtain deep in-sight understanding of structural features.

Automated summary

Polyimide was functionalized and cross-linked to fabricate multi-cationic cross-linked anion-exchange membranes with adjustable properties. These membranes exhibited excellent performance, as well as anti-fouling and anti-bacterial properties, making them suitable for water desalination and other electrochemical applications.