Study of ion exchange media with impedance spectroscopy
Abstract
The ion exchange process is a cost-effective technique that is commonly used to selectively remove detrimental ions from the influent. Typical applications include softening of rural and other water supplies and deionization of water for industrial use. While strong acid cation exchange resins are used to remove the detrimental ions from the urban water supply, the potential of nitrate contamination is still a real concern that can be addressed with strong base anion exchangers. Recent developments have demonstrated that the depletion of an ion exchange bed can be monitored in a water softener or via a remote sensor using impedance measurement techniques. In this study, a frequency of approximately 10 kHz was selected to measure the impedance of the ion exchange bed throughout the regeneration and depletion cycle. Impedance spectroscopy has been used to characterize the electrical behavior of an ion exchanger and has identified two distinct regions which are representative of the bulk and interfacial behavior of the ion bead. Subsequent equivalent circuit modeling of these results provides insight into the behavior of selected anion and cation resins and identifies resins that exhibit distinct electrical performance suitable for sensor applications. This measurement procedure provides an in-situ technique, which can assess the influence of ion exchange operation or manufacturing variables.
This paper has been withdrawn.