A safer route for preparation of anion exchange membrane from inter-polymer film and performance evaluation in electrodialytic application

The present article describes a greener route to inter-polymer anion exchange membranes (AEMs) utilizing p-methylstyrene-co-divinylbenzene (p-MS-co-DVB) in place of styrene-co-divinylbenzene (Sty-co-DVB). Polyvinyl chloride (PVC) and polyethylene (PE) were used as binders and films were prepared from the inter-polymers by solution casting and melt extrusion processes, respectively. Functionalization of the films was effected through benzylic mono-bromination followed by quaternization with trimethylamine. This alternative procedure dispensed with the use of chloromethyl ether (CME) which was required for functionalization of styrene-co-DVB-based polymer films. CME is a carcinogen that is hazardous to health. The AEMs were characterized by Fourier transform infrared spectroscopy, solid-state 13C-nuclear magnetic resonance and scanning electron microscopy, as well as by measurements of ion-exchange capacity, water uptake, mechanical properties (stress–strain curve), and electrical properties such as ionic resistance and transport number. The p-MS-co-DVB/PE AEM, exhibited high transport number (0.95 by the EMF method; NaCl electrolyte) and the electrodialytic desalination efficiency exceeded that of the Sty-co-DVB/PE interpolymer AEM prepared previously. It also exhibited excellent mechanical strength and stability.