Doi Shoichi, Takumi Nobuya, Kakihana Yuriko, Higa Mitsuru
Astom Corporation, 1-1 Mikagecho, Syunan, Yamaguchi 745-8648, Japan.
Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan.
Membranes (Basel). 2020 Sep 11;10(9):228. doi: 10.3390/membranes10090228.
Systematic alkali immersion tests of cation-exchange membranes (CEM) with polyvinyl chloride (PVC) as their backing and binder were conducted to compare that of an Anion-exchange membrane (AEM) with the same PVC materials to investigate the mechanism of dehydrochlorination. In the immersion tests, originally colorless and transparent AEM turned violet, and chemical structure analysis showed that polyene was produced by the dehydrochlorination reaction. However, the CEM did not change in color, chemical structure or membrane properties during the test with less than 1M alkali solutions. According to the Donnan equilibrium theory and the experiments using CEM and AEM, the hydroxide ion concentration in the CEM was much lower than that in the AEM under the same conditions. However, when the alkali immersion test was performed using the CEM under more severe conditions (6 M for 168 h at 40 °C), there was a slight change in the color and chemical structure of the CEM, clearly indicating that not only AEMs, but also CEMs with PVC matrixes were deteriorated by alkali, depending on the conditions.
对以聚氯乙烯（PVC）为支撑体和粘合剂的阳离子交换膜（CEM）进行了系统的碱浸泡试验，以比较相同PVC材料的阴离子交换膜（AEM）的碱浸泡试验情况，从而研究脱氯化氢的机理。在浸泡试验中，原本无色透明的AEM变成了紫色，化学结构分析表明脱氯化氢反应产生了多烯。然而，在使用浓度低于1M的碱溶液进行试验时，CEM的颜色、化学结构或膜性能并未发生变化。根据唐南平衡理论以及使用CEM和AEM进行的实验，在相同条件下，CEM中的氢氧根离子浓度远低于AEM中的氢氧根离子浓度。然而，当在更严苛的条件下（40℃下6M，168小时）对CEM进行碱浸泡试验时，CEM的颜色和化学结构出现了轻微变化，这清楚地表明，不仅AEM，具有PVC基体的CEM也会因碱而劣化，这取决于具体条件。
