Alternative preparative route for efficient and stable anion-exchange membrane for water desalination by electrodialysis

Abstract

We disclosed an alternative method for controlled chloromethylation of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) in presence of paraformaldehyde, tri-methyl chlorosilane and Lewis acid catalyst. About 35–74% degree of chloromethylation (DCM) of PPO was achieved under optimized conditions. Reported method avoids the use of hazardous chemicals (such as chloromethyl methyl ether, and bromine) during preparation of AEM. AEMs with varied DCM were extensively characterized by measuring their physicochemical and electrochemical properties. Reported AEM-3 (DCM: 74%), was designed to possess all the required properties such as good water uptake (26.2%), ion-exchange capacity (1.61meq·g−1), high permselectivity (0.98), and conductivity (7.67×10−2Scm−1) due to high molality of quaternary ammonium groups. Chronopotentiometry study of prepared membranes confirmed their homogeneous and alkaline nature suitable. Most optimized AEM-3 with splendid alkaline, oxidative and hydrolytic stabilities is a good candidate for electrodialysis.