The feasibility of boron removal from water by capacitive deionization

• Published in: Electrochimica acta Vol. 56; no. 18; pp. 6312 - 6317
• Main Authors: Avraham, Eran, Noked, Malachi, Soffer, Abraham, Aurbach, Doron
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15.07.2011; Elsevier
• Subjects: Applied sciences; Boric acids; Boron; Boron removal; Capacitive deionization; Carbon; Charging; Deionization; Electro-adsorbtion; Electrodes; Exact sciences and technology; General purification processes; Pollution; Surface chemistry; Wastewaters; Water treatment and pollution; Capacitive deionization; Electro-adsorbtion; Boron removal; Water; Removal; Porous electrode; Electrochemical method; Carbon; Discharge charge cycle; Boron; Adsorption; Activated carbon; Desalination; Deionization
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2011.05.037

► Boron removal by electrochemical means. ► Temporary local pH changes developed within the pores were indicated by using MgCl2 in the solution as a probe. ► The process of Boron extraction from water takes place in two stages: 1. dissociation of boric acid on the negatively polarized electrode. 2. Electro-adsorption of borate ion onto the positively polarized electrode. We report on the possibility of removing boron (in the form of boric acid) from water by electrochemical means. We explore capacitive de-ionization (CDI) processes in which local changes in pH near the surface of high-surface-area activated carbon fiber (ACF) electrodes during charging are utilized, in order to dissociate boric acid into borate ions which can be electro-adsorbed onto the positive electrode in the CDI cells. For this purpose, a special flow-through CDI cell was constructed in which the feed solution flows through the electrodes. Local pH changes near the carbon electrode surface were investigated using a MgCl2 solution probe in three- (with reference) and two-electrode cells, and described qualitatively. We show that, to a certain extent, boron can indeed be removed from water by CDI.