A versatile chemistry platform for the fabrication of cost-effective hierarchical cation and anion exchange membranes

This work presents a versatile chemistry platform for the fabrication of hierarchical cation and anion exchange membranes (hCEMs and hAEMs) with tuneable transport properties. A strong focus was put onto developing cost-effective membranes fabricated through a sustainable and easily scalable process, with performance at least as good as industry standard materials. Hierarchical ion exchange membranes were fabricated by coating and UV crosslinking an acrylic ionomer on top of a PVC-SiO2 porous substrate. Membrane samples with different crosslinking density of the coating were fabricated and tested for application in electrodialysis-desalination. The properties of hCEMs were found to be strongly dependant on the coating crosslinking density: the hCEM with the least crosslinked coating showed a selectivity of 88% (electrical resistance of 6.15 Ω.cm2), while the one with the most crosslinked coating showed a selectivity of 97% (electrical resistance of 11.02 Ω.cm2). A similar trend was observed for hAEMs for which an increase of the selectivity from 88% to 94% was observed (increase in electrical resistance from 5.22 Ω.cm2 to 6.44 Ω.cm2). The best performing hIEMs allowed to reach an ED current efficiency as high as 93.3% with a final desalination of 56% (commercial reference: current efficiency 94.5%, final desalination 59%).