| 摘要 |
PURPOSE:To obtain an anionic exchange membrane with a low content of impurities suitable for regenerating a stable color developing solution, by treating an anionic exchange membrane containing quaternary ammonium groups with a nitrate. CONSTITUTION:An anionic exchange membrane containing quaternary ammonium groups, e.g. total four H atoms in ammonium ions are substituted by alkyl groups, e.g. methyl groups, is dipped in an aqueous solution of a nitrate, e.g. nitic acid or lithium nitrate, preferably in 0.2-2.0 N concentration, particularly at 10-40 deg.C, and repeatedly washed several times to give the aimed anionic exchange membrane. |
