Abstract
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.
Highlights
The electrodialysis (ED) processes using hydrocarbon ion-exchange membranes (IEMs) have been used for almost half a century to produce salts from seawater, desalination from brackish water or food and beverages, and valuable salt recovery from wastewater treatment in the chemical industry.It has been widely applied to various types of industries [1]
When the alkali immersion test was performed using the cation-exchange membranes (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 anion-exchange membrane (AEM), and CEMs with polyvinyl chloride (PVC) matrixes were deteriorated by alkali, depending on the conditions
Neosepta® CMX was used as the commercial homogeneous CEM, and Neosepta® AMX was used as the homogeneous AEM in this study
Summary
The electrodialysis (ED) processes using hydrocarbon ion-exchange membranes (IEMs) have been used for almost half a century to produce salts from seawater, desalination from brackish water or food and beverages, and valuable salt recovery from wastewater treatment in the chemical industry. It has been widely applied to various types of industries [1] While it can be considered as a mature technology, the research and development of the ED process has still been active.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
