In-situ interfacial polymerization endows surface enrichment of -COOH groups on anion exchange membranes for efficient Cl-/SO42- separation

In-situ interfacial polymerization (ISIP) technique is developed to prepare monovalent anion-permselective membranes (MAPMs). The introduction of multi-hydroxyl (-OH) and cationic groups in the base membrane provide suitable routes towards the monovalent anion transport. Only trimesoyl chloride (TMC) is employed to generate a crosslinked polyester layer on membrane surface. The ISIP transforms the surface of anion exchange membranes into a dense and negatively charged layer to promote the ion permselectivity. The modified membranes show a high limiting current density and low membrane resistance of 4.7 Ω.cm². The resultant membranes exhibit a high Cl^- flux of 6.3 × 10^-8 mol cm^-2 s^-1 and a high permselectivity of ~60 for Cl^-/SO₄^2-. The findings demonstrate the ISIP technique having great potentials for the fabrication of highly permselective MAPMs.

Keywords: Monovalent anion permselective membranes, In-situ interfacial polymerization, Anion separation,  Permselectivity, Ionic flux,  Electrodialysis