Selective ion separation by capacitive deionization (CDI) based technologies: A state-of-the-art review
Selective ion extraction from aqueous solution is of great significance for water purification as well as resource recovery. Capacitive deionization (CDI), as an emerging desalination technology, has been introduced to selectively remove target ionic contaminants in the past few years. Due to tailorable electrode material and interface and flexible operation, CDI exhibits great superiority in regulating the ion electrosorption process thus realizing considerable selective adsorption for target contaminant. In this paper, we propose an overview of current status of selective ion adsorption in CDI systems. The mechanism of selectivity is mainly illustrated through regulating ion migration on electrode interface or adsorption in bulk electrode. The applied materials and strategies include (pseudo) capacitive materials, interface membranes/coatings, faradaic reactions and operation optimization. This review also discusses the prospect of selective CDI including its performance evaluation, purpose, application scope, challenge etc., which helps to inform future research in terms of addressing knowledge gaps in developing and applying selective CDI systems.
- This article is part of the themed collection: Capacitive Deionisation 2020