Electrode degradation mechanisms in capacitive deionisation

The present study deals with the development and characterisation of a carbon electrode for the process of capacitive deionisation (CDI). Special attention was paid to an analysis of the decline in electrode performance over time and to a more detailed understanding of the related degradation processes. Besides electrode blockage by Ca2+ and Mg2+ precipitates, an additional degradation process, resulting in an irreversible electrode surface modification reducing its salt adsorption capacity, was identified. The mechanism of electrode surface modification based on the anodic oxygen evolution reaction, as well as the interaction of the surface modified by on this way formed oxygen containing functional groups with charged species present in the treated water, were discovered. A method of preventing or at least reducing the above-mentioned degradation process is proposed.

Automated summary

The study focused on the development and characterization of a carbon electrode for capacitive deionisation (CDI), as well as understanding the degradation processes leading to decline in electrode performance over time. An additional degradation process causing irreversible electrode surface modification reducing salt adsorption capacity was identified, along with the mechanism of electrode surface modification based on the anodic oxygen evolution reaction. A method for preventing or reducing the degradation process was proposed.