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  5. Exploiting water contaminants: In-situ electrochemical generation of ferrates using ambient raw water iron (Fe2+)
 
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Exploiting water contaminants: In-situ electrochemical generation of ferrates using ambient raw water iron (Fe2+)
File(s)
JECE - Manuscript - McBeath, Wilkinson, Graham - Revised.pdf (1.3 MB)
Accepted version
Author(s)
McBeath, Sean T
Wilkinson, David P
Graham, Nigel JD
Type
Journal Article
Abstract
Many complexities arise when applying conventional water treatment processes to small and remote systems. A significant challenge is the difficulty and impracticality of supplying chemicals needed for oxidation processes. A burgeoning, yet currently under-utilised, type of treatment are electrochemical technologies, which are receiving considerable research attention and innovation at present. In particular, through the advancement of high oxygen overpotential electrodes, the ability to synthesise highly oxidative chemical species under circumneutral pH conditions has become possible. In this study, the generation of highly oxidative iron-based species, specifically ferrate (Fe6+), has been explored utilising a boron-doped diamond (BDD) electrode and low concentrations of Fe2+ typically found in raw water, thereby eliminating the chemical supply chain required for conventional oxidation processes. Electrochemical ferrate generation experiments were performed in a batch-recycle configuration and were found to be mass transfer limited, whereby the rate-limiting step was the diffusion of Fe2+ to the electrode surface. This was evidenced by very little variation in ferrate generation at the three current densities tested, specifically 3.1 ± 0.2, 2.6 ± 0.2 and 3.3 ± 0.2 μM were generated at 10, 40 and 80 mA/cm2, respectively. Measured Fe6+ concentrations correlated well with those predicted by a mathematical process model, which assumed a completely mass transport limited process. While cyclic voltammetry confirmed ferrate generation by direct oxidation at the BDD surface, the contribution of hydroxyl radicals was indicated by the presence and absence of methanol, an radical dotOH scavenger, with ferrate generation decreased by greater than 50 % with methanol, compared to non-scavenged experiments. The results provide one of the first quantitative studies regarding the oxidation mechanisms of ferrate generation by electro-oxidation, and the first example of ferrate generation at circumneutral pH from Fe2+ at levels representative of raw water.
Date Issued
2020-08-01
Date Acceptance
2020-03-04
Citation
Journal of Environmental Chemical Engineering, 2020, 8 (4), pp.1-9
URI
http://hdl.handle.net/10044/1/82899
URL
https://www.sciencedirect.com/science/article/pii/S2213343720301822?via%3Dihub
DOI
https://www.dx.doi.org/10.1016/j.jece.2020.103834
ISSN
2213-3437
Publisher
Elsevier
Start Page
1
End Page
9
Journal / Book Title
Journal of Environmental Chemical Engineering
Volume
8
Issue
4
Copyright Statement
© 2020 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence http://creativecommons.org/licenses/by-nc-nd/4.0/
License URL
http://creativecommons.org/licenses/by-nc-nd/4.0/
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000563932900005&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Technology
Engineering, Environmental
Engineering, Chemical
Engineering
Electrochemical oxidation
Water treatment
Boron doped diamond
Ferrate
Iron
Hydroxyl radicals
DOPED DIAMOND
ANODIC-DISSOLUTION
CURRENT EFFICIENCY
OXYGEN EVOLUTION
CURRENT YIELDS
CAST-IRON
OXIDATION
ELECTRODES
HYDROGEN
INACTIVATION
Publication Status
Published
Article Number
ARTN 103834
Date Publish Online
2020-03-05
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