Development of Novel Ion-Exchange Membranes for Electrodialysis of Seawater Prepared by Electron-Beam-Induced Graft Polymerization
(III) Co-Graft Polymerization of Glycidyl Methacrylate and Divinylbenzene onto High-Density Polyethylene Film

Abstract

Glycidyl methacrylate (GMA), an epoxy-group-containing monomer, was graft-polymerized onto a high-density polyethylene (HDPE) film with a thickness of 35μm. Divinyl benzene (DVB) was co-grafted as a cross-linker. Toluene used as a solvent of a mixture of GMA and DVB provided a uniform density of the grafted polymer chain across the membrane. Subsequently, the produced epoxy group was converted into anion and cation-exchange groups by a reaction with trimethylammonium chloride and sodium sulfite, respectively. The resultant anion- and cation- exchange membranes exhibited 0.55 and 0.34Ωcm², respectively, which were lower membrane resistances with ion-exchange capacity comparable to commercially available ion-exchange membranes. The highest brine concentration of 3.7mol/L for electrodialysis of 0.50mol/L sodium chloride as a model seawater was attained using the ion-exchange membranes prepared from GMA/DVB-co-grafted membranes with a DVB mole percentage of 1.0mol%.