Efficient separation of bismuth(III) by tertiary amine-functionalized polymeric membranes in electrodialysis

Efficient separation of technology-critical bismuth from diverse waste streams and mineral processing is of high significance. However, Bi(III) coexists with various metal ions that have similar physicochemical properties, making its selective recovery challenging. Herein, tertiary amine-functionalized polymeric membranes with prominent bismuth separation performance are fabricated using a solvent casting pore-filling method. The excellent compatibility between the trioctylamine and polymer chains facilitates the construction of continuous ion channels, thereby enabling highly efficient and selective separation of Bi(III) during electrodialysis. The fabricated membrane achieve a great Bi(III) flux of 131.0 × 10⁻² mmol m⁻² h⁻¹ and ultrahigh perm-selectivity values (i.e., $P_{Cu\left(II\right)}^{Bi\left(III\right)}$ = 483.9, $P_{Ni\left(II\right)}^{Bi\left(III\right)}$ = 40499.7, $P_{Co\left(II\right)}^{Bi\left(III\right)}$ = 27663.1, $P_{Fe\left(III\right)}^{Bi\left(III\right)}$ = 378.3, $P_{Cr\left(III\right)}^{Bi\left(III\right)}$ = 819.1, $P_{Mn\left(II\right)}^{Bi\left(III\right)}$ = 2014.9, and $P_{Al\left(III\right)}^{Bi\left(III\right)}$ = 505.6) in the presence of multiple metal ions, which is much superior to that of flagship commercial AGU. The good stability of the membrane demonstrates bright prospects for realizing efficient bismuth recovery in industrial-scale applications.