Anion exchange membrane

Japanese: 陰イオン交換膜 - いんいおんこうかんまく

… Ion exchange resins in the form of membranes are specifically called ion exchange membranes. They are essentially the same as ion exchange resins, with sulfonic acid groups used for cation exchange membranes and quaternary ammonium groups used for anion exchange membranes. Cations such as Na ⁺ and Ca ²⁺ are permeable through cation exchange membranes but anions are not. Conversely, anion exchange membranes are permeable to anions such as Cl ^- and SO ₄ ^2- but not to cations. …

From [Salt]

... The ion exchange membrane method is an excellent technique for extracting brine that was developed and put to practical use in Japan. It is a method for extracting about 20% brine from seawater with about 3% sodium chloride. As shown in Figure 2, the principle is that seawater is placed in a tank in which membranes (cation exchange membranes) that allow only positive ions such as sodium ions, potassium ions, and magnesium ions to pass through and membranes (anion exchange membranes) that allow only negative ions such as chloride ions and sulfate ions to pass through are arranged alternately, and when direct current electricity is passed from both sides, the electricity transports the ions through the membranes, producing concentrated seawater and dilute seawater in alternating layers (this is called electrodialysis). This concentrated seawater (brine) with about 20% sodium chloride is collected and boiled in a vacuum evaporator to obtain salt crystals. ...

*Some of the terminology that refers to "anion exchange membrane" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…　イオン交換樹脂を膜状にしたものは，とくにイオン交換膜と呼ばれる。本質的にはイオン交換樹脂と同じであり，陽イオン交換膜にはスルホン酸基が，陰イオン交換膜には第四アンモニウム基が用いられている。陽イオン交換膜はNa^＋，Ca^2＋などのカチオンは透過するがアニオンは透過せず，逆に陰イオン交換膜はCl^－，SO₄^2－などのアニオンは透過するがカチオンは透過しない。…

【塩】より

…　イオン交換膜法とは，日本で開発，実用化された優れた鹹水採取技術で，塩化ナトリウム3％程度の海水から同じく20％程度の鹹水を採取する方法である。その原理は，図2に示すように，ナトリウムイオン，カリウムイオン，マグネシウムイオンのような陽イオンのみを通す膜(陽イオン交換膜)と塩素イオン，硫酸イオンのような陰イオンのみを通す膜(陰イオン交換膜)を交互に並べた槽に海水を入れ，両側から直流電気を通すと，電気によりイオンが膜を通って運ばれて一つおきに濃い海水と薄い海水とができる(これを電気透析という)。この20％程度の濃い海水(鹹水)を集めて，真空蒸発缶で煮つめて塩の結晶を得る方法である。…

※「陰イオン交換膜」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典第２版について | 情報

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