Concentration polarization in electrodialysis: Buffer solutions experimental method

This research work compares the electrodialytic properties of NiSO4 and NiCl2 during a batch process. The current intensitytime, pH-time, water transport-time plottings are investigated. We try to answer the following questions: (1) Why do NiSO4 and NiCl2 present very different electrodialytic properties? (2) Is it possible to anticipate the electrodialytic behavior and properties of a given salt? (3) What are the salt basic properties that influence directly its electrodialytic behavior? The pH-time curves are the more interesting results: the pH decreases with NiSO4 and increases with NiCl2. The classical approaches do not explain this difference. In this study we try to defend this idea: the difference of the counterions mobilities in their respective membranes explains the pH changes.