Pilot-scale poly(alkyl-biphenyl pyridine)-based monovalent anion perm-selective membranes with exceptional Cl−/SO42− selectivity in ion-distillation

Monovalent anion perm-selective membranes (MAPMs) were fabricated from poly(alkyl-biphenyl pyridine) backbone via Menshutkin reaction and in-situ thermal crosslinking. Compared to the commercial ACS membrane (Cl- flux of 2.44 mol m-2 h-1, selectivity of 5.55), the optimum MAPM exhibited superior Cl- ions flux of 2.78 mol m-2 h-1 and Cl-/SO42- selectivity of 10.5 at current density of 10 mA cm-2. Additionally, the optimum MAPM was successfully scaled up and comprehensively evaluated, demonstrating exceptional ion separation performance and operational stability. Notably, in the ion-distillation process, the scale-up membrane displayed an extremely high separation coefficient of Cl-/SO42- over 15,000. The membrane shows promise for practical applications in treating high salt wastewater and desalination processes requiring Cl-/SO42- separation.