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ChemSusChem. 2018 Oct 11;11(19):3460-3472. doi: 10.1002/cssc.201801538. Epub 2018 Aug 22.

Confined Redox Reactions of Iodide in Carbon Nanopores for Fast and Energy-Efficient Desalination of Brackish Water and Seawater.

Author information

1
INM-Leibniz Institute for New Materials, Campus D2 2, 66123, Saarbrücken, Germany.
2
Department of Materials Science and Engineering, Saarland University, Campus D2 2, 66123, Saarbrücken, Germany.
3
School of Energy, Materials, and Chemical Engineering, Korea University of Technology and Education, 1600 Chungjeol-ro, Cheonan, 31253, Republic of Korea.
4
Department of Chemical Engineering, Federal University of São Carlos, 13565-905, São Carlos, Brazil.

Abstract

Faradaic deionization is a promising new seawater desalination technology with low energy consumption. One drawback is the low water production rate as a result of the limited kinetics of the ion intercalation and insertion processes. We introduce the redox activities of iodide confined in carbon nanopores for electrochemical desalination. A fast desalination process was enabled by diffusionless redox kinetics governed by thin-layer electrochemistry. A cell was designed with an activated carbon cloth electrode in NaI aqueous solution, which was separated from the feedwater channel by a cation-exchange membrane. Coupled with an activated carbon counter electrode and an anion-exchange membrane, the half-cell in NaI with a cation-exchange membrane maintained performance even at a high current of 2.5 A g-1 (21 mA cm-2 ). The redox activities of iodide allowed a high desalination capacity of 69 mg g-1 (normalized by the mass of the working electrode) with stable performance over 120 cycles. Additionally, we provide a new analytical method for unique performance evaluation under single-pass flow conditions regarding the water production rate and energy consumption. Our cell concept provides flexible performance for low and high salinity and, thus, enables the desalination of brackish water or seawater. Particularly, we found a low energy consumption (1.63 Wh L-1 ) for seawater desalination and a high water production rate (25 L m-2  h-1 ) for brackish water.

KEYWORDS:

deionization; desalination; electrochemistry; energy recovery; redox chemistry

PMID:
30066492
DOI:
10.1002/cssc.201801538

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