Electrically regenerated ion-exchange technology: Leveraging faradaic reactions and assessing the effect of co-ion sorption

Capacitive deionization (CDI) technologies have the potential to become cost-competitive alternatives to reverse osmosis for the treatment of brackish waters. In this study, we report our findings on the effect of co-ion sorption and faradaic side reactions on our ion exchange resin functionalized desalination electrodes which passively capture salt and reject it upon charging. This system, which we previously reported on and refer to as electrically regenerated ion exchange (ERI), avoids the use of expensive ion exchange membranes in an effort to save costs. Surprisingly, we find that, compared to a reference CDI system, ERI electrodes capture salt most effectively at low applied voltages (0.5 mg/cm3 at 0.8 V). Both CDI and ERI systems also seem to suffer from co-ion sorption effects which negatively impact salt adsorption. However, Faradaic side reactions at higher voltages (1 V and 1.2 V) which we track via pH measurements, serve as a detriment to CDI but seem to facilitate the functionality of ERI. (c) 2022 Elsevier Inc. All rights reserved.

Automated summary

Capacitive deionization (CDI) technologies have the potential to replace reverse osmosis as cost-competitive alternatives for brackish water treatment. This study investigates the impact of co-ion sorption and faradaic side reactions on ion exchange resin functionalized desalination electrodes. The findings show that the electrically regenerated ion exchange (ERI) system effectively captures salt at low applied voltages, and Faradaic side reactions facilitate the functionality of ERI.