Commercially available activated carbon cloth electrodes are treated using nitric acid and ethylenediamine solutions, resulting in chemical surface charge enhanced carbon electrodes for capacitive deionization (CDI) applications. Surface charge enhanced electrodes are then configured in a CDI cell to examine their salt removal at a fixed charging voltage and both reduced and opposite polarity discharge voltages, and subsequently compared to the salt removal of untreated electrodes. Substantially improved salt removal due to chemical surface charge and the use of a discharge voltage of opposite sign to the charging voltage is clearly demonstrated in these CDI cycling tests, an observation which for the first time validates both enhanced CDI and extended-voltage CDI effects predicted by the Donnan model [Biesheuvel et al., Colloids Interf. Sci. Comm., 10.1016/j.colcom.2015.12.001 (2016)]. Our experimental and theoretical results demonstrate that the use of carbon electrodes with optimized chemical surface charge can extend the CDI working voltage window through discharge voltages of opposite sign to the charging voltage, which can significantly enhance the salt adsorption capacity of CDI electrodes. Thus, in addition to carbon pore size distribution, chemical surface charge in carbon micropores is considered foundational for salt removal in CDI cells.
|Number of pages||8|
|State||Published - Apr 1 2016|
Bibliographical noteFunding Information:
X.G., A.O., K.-L.L., and J.L. are grateful to the U.S. - China Clean Energy Research Center, U.S. Department of Energy for project funding (Award No. DE-PI0000017 ) and the National Science Foundation (Award No. 1520226 ). Part of this work was performed in the cooperation framework of Wetsus, European Centre of Excellence for Sustainable Water Technology ( www.wetsus.eu ). Wetsus is co-funded by the Dutch Ministry of Economic Affairs and Ministry of Infrastructure and Environment , the Province of Fryslân, and the Northern Netherlands Provinces.
© 2016 Elsevier Ltd.
- Amphoteric Donnan model
- Capacitive deionization
- Enhanced salt removal
- Extended working voltage window
ASJC Scopus subject areas
- Water Science and Technology
- Ecological Modeling
- Waste Management and Disposal
- Environmental Engineering
- Civil and Structural Engineering