Interaction of cation‐exchange membrane with polycation. II. Poly(N‐alkyl‐4‐vinylpyridinium halides)

The effect of the hydrophile–lipophile balance (HLB) of poly(N‐alkyl‐4‐vinylpyridinium halides) (PAVP) on the interaction between PAVP and the cation‐exchange membrane was elucidated by using various alkyl groups: methyl, ethyl, octyl, and so on. In the electrodialytic concentration of sea water by using the membrane on which PAVP has been adsorbed or ion‐exchanged, the ratio of monovalent cations to total cations in the concentrated brine, β (Na+K), is almost same at the initial stage in species of PAVP. However, the deterioration ratio of β(Na+K) is smaller with decreasing HLB. In order to obtain the large value of β(Na+K), poly(N‐methyl and dodecyl‐4‐vinylpyridinium chloride) (PMDVP), was investigated. PMDVP, of which the ratio of pyridinium groups quaternized with 1‐bromododecane to total pyridinium groups (Qd) is about 40%, shows high initial value of β(Na+K) and its good durability.