Perez, JPH, Tobler, DJ, Freeman, HM orcid.org/0000-0001-8242-9561 et al. (4 more authors) (2021) Arsenic species delay structural ordering during green rust sulfate crystallization from ferrihydrite. Environmental Science: Nano. ISSN 2051-8153
Abstract
Green rust (GR) is an Fe(II)–Fe(III)-bearing phase that forms in oxygen-poor and Fe2+-rich subsurface environments where it influences trace element cycling and contaminant dynamics. GR phases have been shown to have high arsenic (As) uptake under anoxic and circum-neutral pH conditions. While geochemical controls on As uptake by GR have been identified, we still lack a fundamental understanding about GR formation in As-contaminated soils and groundwater, as well as the stability of As-bearing GR solids. In this study, we quantified the influence of As(III) and As(V) ([As]initial = 100 μM) on GR sulfate (GRSO4) crystallization during the Fe2+-induced transformation of ferrihydrite (FHY) at pH 8 (As/Fesolid = 0.008, Fe2+(aq)/Fe(III)FHY = 3). We also documented the behavior of mineral-bound As during GRSO4 crystallization and its transformation to magnetite. Our results showed that, compared to the As-free system, adsorbed As species delayed FHY transformation to GRSO4. Moreover, As(III) had a stronger inhibitory effect (at least eight-fold) than As(V) on GRSO4 crystallization, and reduced structural coherence and ordering in As(III)-bearing GRSO4 crystals. During FHY dissolution, we observed an initial release of ∼14 μM As(III) into the aqueous phase, but this was quickly adsorbed by newly-formed GRSO4 crystals. Mineral-bound As(III) resulted in at least four-fold increase in GRSO4 phase stability compared to As(V), and fully prevented its transformation to magnetite even after 720 h. Our results provide new information on the pathways of interaction of common Fe phases exposed to reducing, Fe2+-bearing and As-contaminated fluids and how these affect the structure, morphology and stability of As-bearing GR phases.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © The Royal Society of Chemistry 2021. This is an author produced version of an article, published in Environmental Science: Nano. Uploaded in accordance with the publisher's self-archiving policy. |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemical & Process Engineering (Leeds) The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Civil Engineering (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 14 Sep 2021 10:37 |
Last Modified: | 23 Aug 2022 00:13 |
Status: | Published online |
Publisher: | Royal Society of Chemistry |
Identification Number: | 10.1039/d1en00384d |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:178171 |