Assessing Iron Complexation by Dissolved Organic Matter Using Mediated Electrochemical Oxidation

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Author(s)Hudson, Jeffrey M.
Author(s)Luther, George W., III
Author(s)Chin, Yu-Ping
Date Accessioned2024-10-09T19:37:52Z
Date Available2024-10-09T19:37:52Z
Publication Date2024-08-14
DescriptionThis document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Earth and Space Chemistry, copyright © 2024 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acsearthspacechem.4c00131. This article will be embargoed until 08/14/2025.
AbstractFeII is an abundant reductant in the environment that participates in numerous biogeochemical cycles and pollutant attenuation. FeII in aquatic environments can exist as a complex with dissolved organic matter (DOM), where organic ligands in DOM can modulate iron’s redox potential (EH) and henceforth reactivity as a reductant. Previous studies have assessed the reactivity of FeII-complexes using probe compounds, although these compounds are limited in their ability to profile FeII oxidation across multiple thermodynamic conditions (i.e., both pH and EH) and fail to validate the EH of Fe(II)-complexes via their direct measurement. This study elucidated the redox potentials of FeII-DOM complexes via mediated electrochemical oxidation (MEO) and assessed the extent of FeII oxidation at two different applied EH and pH regimes. Furthermore, we used a Nernstian-based model calibrated with a training set between known iron-ligand thermodynamic stability constants and their respective measured potentials to indirectly determine the stability constants of both FeII and FeIII-DOM complexes as a function of EH and pH. This work highlights the versatility of MEO as an electrochemical technique and is the first to assess stability constants of Fe-complexes with aquatic DOM isolates. We also discuss linkages between speciation modeling and redox reactivity of FeII.
SponsorFunding for this project was made possible through a US Department of Energy Office of Science SCGSR fellowship program supporting J.M.H.’s PhD research, along with NSF grant number 2029665.We would also like to thank Pei Chiu and Dominic DiToro for their insightful comments throughout the preparation of this manuscript.
CitationHudson, Jeffrey M., George W. III Luther, and Yu-Ping Chin. “Assessing Iron Complexation by Dissolved Organic Matter Using Mediated Electrochemical Oxidation.” ACS Earth and Space Chemistry 8, no. 9 (September 19, 2024): 1810–19. https://doi.org/10.1021/acsearthspacechem.4c00131.
ISSN2472-3452
URLhttps://udspace.udel.edu/handle/19716/35211
Languageen_US
PublisherACS Earth and Space Chemistry
KeywordsFe(II)
KeywordsDOM
Keywordsligand
Keywordsredox potential
Keywordsstability constant
KeywordsMEO
Keywordslife below water
Keywordslife on land
TitleAssessing Iron Complexation by Dissolved Organic Matter Using Mediated Electrochemical Oxidation
TypeArticle
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