Effect of aminating agents on the permselectivity for nitrate of aminated poly(vinyl benzylchloride-co-styrene-co-hydroxy ethylacrylate) membranes

Poly(vinyl benzylchloride-co-styrene-co-hydroxy ethylacrylate) anion exchange membranes were synthesized via free radical polymerization. To determine the membrane properties relative to the bulkiness of the aminating agent, these solutions were aminated with various aminating agents, including trimethylamine, triethylamine, tripropylamine and tributylamine. The structures of the aminated copolymer solutions were confirmed by Fourier transform infrared (FT-IR) analysis. The membrane properties, such as water content, ion exchange capacity, electrical resistance, ion conductivity and permselectivity for nitrate, were also measured. The maximum water content, ion exchange capacity, electrical resistance and ion conductivity were 45.5%, 0.90 meq/g dry membrane, 60.2 Ω cm2 and 0.0109 S/cm, respectively. The membrane aminated with tributylamine was permeable to considerably lower amounts of anions but had higher permselectivity for the nitrate anion than the other membranes aminated with trimethylamine, triethylamine and tripropylamine.