A comparative study on electrosorptive rates of metal ions in capacitive deionization. (December 2018)

• Record Type: Journal Article
• Authors: Li, Yanting; Stewart, Ty C.; Tang, Hao L.
• Is Part Of: Journal of water process engineering. Volume 26(2018)
• Page Start: 257
• Page End: 263
• Publication Date: 2018-12
• Subjects: Electrosorption -- Heavy metal -- Ionic hydrated radius -- Kinetics -- Capacitive deionization; Water-supply engineering -- Periodicals; Saline water conversion -- Periodicals; Seawater -- Distillation -- Periodicals; Sanitary engineering -- Periodicals; Sewage -- Purification -- Periodicals; 627
• DOI: 10.1016/j.jwpe.2018.10.021
• Languages: English
• ISSNs: 2214-7144

Abstract

Highlights: Electrosorption of different metal ions in mono-component solutions were studied. Electrosorptive kinetics of tested metal ions followed the Lagergren equation. Ionic hydrated radii dictated the order of electrosorptive rates except Cu 2+ and Pb 2+ . Cu 2+ and Pb 2+ showed serious electrode fouling potential during the CDI treatment. Abstract: A comparative study on electrosorptive rates was conducted to explore the affinity preference of Na +, K +, Mg 2+, Ca 2+, Cd 2+, Pb 2+ and Cu 2+ to activated carbon cloth electrodes of capacitive deionization (CDI) in mono-component solutions. Results showed the electrosorptive kinetics of these metal ions followed the Lagergren equation. For alkali and alkali-earth metal ions, the order of electrosorptive rates followed K + > Na + > Ca 2+ > Mg 2+, which revealed an inversely proportional relationship with their ionic hydrated radii. The relationship between electrosorptive rates and ionic hydrated radii, however, did not hold for heavy metal ions, and the order was Cu 2+ > Pb 2+ > Cd 2+ . The abnormal electrosorptive behaviors of Cu 2+ and Pb 2+ could be attributed to electrodeposition and formation of OH − complexes during electrosorption. Besides, Cu 2+ and Pb 2+ showed significantly low desorption efficiencies during the electrode regeneration processes, indicating serious electrode fouling during the electrosorptive process. This work provides fundamental aspects on individual removal of metal ions and the results can be beneficially used as a reference for treatment and recovery of metal ions by CDI technology.