Synthesis of a quaternarized poly(vinylimidazole-co-trifluoroethylmethacrylate-co-divinylbenzene) anion-exchange membrane for nitrate removal

• Copolymer solutions were quaternized with various functional agents.
• Preparation of nitrate ion selective membrane.
• A partially fluorinated anion exchange membrane was prepared by the casting method.
• Fundamental properties and permselectivities for nitrate were measured.
• Nitrate ion-selective constant of synthesised membranes was calculated.

The effect of functional agents on the ion permselectivity between an anion exchange membrane and solutions of electrolytes containing the most dominant anions of natural waters (Cl−, NO3− and SO42−) was studied. The vinylimidazole(VI)-co-trifluoroethylmethacrylate(TFEMA)-co-divinylbenzene(DVB) copolymer was synthesized by solution polymerization. The copolymer was functionalized with compounds such as 1-bromo-2-methylpropane, 1-bromobutane, 1-bromo-3-methylbutane and 1-bromopentane. Quaternarized poly(vinylimidazole-co-trifluoroethylmethacrylate-co-divinylbenzene) (QPVTD) anion exchange membranes were prepared using the casting method. The molecular structure of the membrane was confirmed by Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. The membrane properties, such as water uptake, ion exchange capacity, electrical resistance and ion permselectivity for nitrate, were measured. The maximum water uptake, electrical resistance and ion exchange capacity were 60.8%, 3.7 Ω/cm2 and 1.25 meq/g dry, respectively.