Active and Selective Transport of Anions through Membranes of Vinylpyridine-Styrene Copolymers

Abstract

Membranes having pyridine moieties as fixed carriers for anion transport were mede from copolymers of styrene(St) and vinylpyridine monomers such as 4-vinylpyridine(4 VPy), 3vinylpyridine(3 VPy), 2-methyl-5-vinylpyridine(2 M 5 VPy), or 2-vinylpyridine(2 VPy).
Anions were transported through these membranes against its concentration gradient, that is, the active transport of anions was observed. These membranes showed a high selectivity for the transport of anions, namely, the membrane of 4 VPy-St copolymer could transport bromide ion, while it didn't transport chloride ion. On the other hand, the membrane of 2 VPy-St copolymer could transport only chloride ion with rejection of bromide ion. This high selectivity is given by the affinity between the carrier and anion, i. e., the incorporation of anions into the membrane.