Intercalation of aromatic sulfonates in ‘green rust’ via ion exchange

Perez, Jeffrey Paulo H.; Mangayayam, Marco C.; Rubio, Sandra Navaz; Freeman, Helen M.; Tobler, Dominique J.; Benning, Liane G.

doi:10.1016/j.egypro.2018.07.023

Cited by 9 publications

(7 citation statements)

References 27 publications

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“…siderite (amorphous siderite), GR (green rust), Viv (vivianite). The XRD profile for the Green Rust (part b) that matches the pattern for Lep-pH 8.5was reported byPerez et al (2018) 97. The pattern for Lep-pH 8.5 was divided by 5 to fit on the same axis as the other two conditions (part b).…”

supporting

confidence: 70%

“…The XRD profile for the Green Rust (part b) that matches the pattern for Lep-pH 8.5was reported by Perez et al (2018). 97 The pattern for Lep-pH 8.5 was divided by 5 to fit on the same axis as the other two conditions (part b). reactors, the iron reduction rates and fractions of Fe(III) reduced differ by factors as much as 4.4 and 3.3 between the culturing conditions, respectively (Table 1).…”

Section: ■ Discussionmentioning

confidence: 99%

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Controls on Iron Reduction and Biomineralization over Broad Environmental Conditions as Suggested by the FirmicutesOrenia metallireducensStrain Z6

Dong

Sanford

Boyanov

et al. 2020

Environ. Sci. Technol.

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Microbial iron reduction is a ubiquitous biogeochemical process driven by diverse microorganisms in a variety of environments. However, it is often difficult to separate the biological from the geochemical controls on bioreduction of Fe(III) oxides. Here, we investigated the primary driving factor(s) that mediate secondary iron mineral formation over a broad range of environmental conditions using a single dissimilatory iron reducer, Orenia metallireducens strain Z6. A total of 17 distinct geochemical conditions were tested with differing pH (6.5–8.5), temperature (22–50 °C), salinity (2–20% NaCl), anions (phosphate and sulfate), electron shuttle (anthraquinone-2,6-disulfonate), and Fe(III) oxide mineralogy (ferrihydrite, lepidocrocite, goethite, hematite, and magnetite). The observed rates and extent of iron reduction differed significantly with k int between 0.186 and 1.702 mmol L–1 day–1 and Fe(II) production ranging from 6.3% to 83.7% of the initial Fe(III). Using X-ray absorption and scattering techniques (EXAFS and XRD), we identified and assessed the relationship between secondary minerals and the specific environmental conditions. It was inferred that the observed bifurcation of the mineralization pathways may be mediated by differing extents of Fe(II) sorption on the remaining Fe(III) minerals. These results expand our understanding of the controls on biomineralization during microbial iron reduction and aid the development of practical applications.

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confidence: 70%

Section: ■ Discussionmentioning

confidence: 99%

Controls on Iron Reduction and Biomineralization over Broad Environmental Conditions as Suggested by the FirmicutesOrenia metallireducensStrain Z6

Dong

Sanford

Boyanov

et al. 2020

Environ. Sci. Technol.

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“…TEM and SEM analyses of the transformation end-products confirmed that GT was the main product with FH still present in all experiments after 24 h. As shown before with XRD and PDF, GR SO4 was only present in reactions with Fe 2+ (aq) /Fe(III) solid = 2 (Figures a, S-5, and S-6). GR SO4 was identified by its thin hexagonal plate-like particles (Figure b), ,, GT by its distinctive crystalline nanorod (Figure d), and FH by its ∼3 nm-sized particle aggregates (Figures f and S-5). SEM images of the end-products also revealed that particle lengths of the GT nanorods gradually decreased with increasing Fe 2+ (aq) /Fe(III) solid ratios (Figures S-6 and S-7).…”

Section: Resultsmentioning

confidence: 99%

Adsorption and Reduction of Arsenate during the Fe²⁺-Induced Transformation of Ferrihydrite

Perez

Tobler

Thomas

et al. 2019

ACS Earth Space Chem.

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Iron (oxyhydr)oxides play an important role in controlling the mobility and toxicity of arsenic (As) in contaminated soils and groundwaters. Dynamic changes in subsurface geochemical conditions can impact As sequestration and remobilization since the fate of As is highly dependent on the dominant iron mineral phases present and, specifically, the pathways through which these form or transform. To assess the fate of arsenate [As(V)] in subsurface settings, we have investigated the Fe2+-induced transformation of As(V)-bearing ferrihydrite (As(V)-FH) to more crystalline phases under environmentally relevant anoxic subsurface conditions. Specifically, we examined the influence of varying Fe2+ (aq)/Fe(III)solid ratios (0.5, 1, 2) on the behavior and speciation of mineral-bound As species during the transformation of As(V)-FH to crystalline iron-bearing phases at circumneutral pH conditions. At all Fe2+ (aq)/Fe(III)solid ratios, goethite (GT), green rust sulfate (GRSO4), and lepidocrocite (LP) formed within the first 2 h of reaction. At low ratios (0.5 to 1), initially formed GRSO4 and/or LP dissolved as the reaction progressed, and only GT and some unreacted FH remained after 24 h. At Fe2+ (aq)/Fe(III)solid ratio of 2, GRSO4 remained stable throughout the 24 h of reaction, alongside GT and unreacted As(V)-FH. Despite the fact that majority of the starting As(V)-FH transformed to other phases, the initially adsorbed As was not released into solution during the transformation reactions, and ∼99.9% of it remained mineral-bound. Nevertheless, the initial As(V) became partially reduced to As(III), most likely because of the surface-associated Fe2+-GT redox couple. The extent of As(V) reduction increased from ∼34% to ∼40%, as the Fe2+ (aq)/Fe(III)solid ratio increased from 0.5 to 2. Overall, our results provide important insights into transformation pathways of iron (oxyhydr)oxide minerals in As contaminated, anoxic soils and sediments and demonstrate the impact that such transformations can have on As mobility and also importantly oxidation state and, hence, toxicity in these environments.

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“…GR sulfate was synthesized following a modified co-precipitation method by Géhin et al by titrating a mixed solution of (NH 4 ) 2 Fe(SO 4 ) 2 ·6H 2 O and Fe 2 (SO 4 ) 3 (Fe(II)/Fe(III) ratio = 3) with NaOH until pH ∼8. , The freshly precipitated GR slurries (∼27 mM Fe tot ) were added with either As(III) or As(V) solution ([As] initial ≈ 6.7 mM) at pH ∼7 and reacted for 5 days. The amount of adsorbed As was determined by inductively coupled plasma optical emission spectroscopy (ICP-OES Varian 720ES) following a method described in Perez et al Further information can be found in the Supporting Information (Text S1).…”

Section: Methodsmentioning

confidence: 99%

Direct Visualization of Arsenic Binding on Green Rust Sulfate

Perez

Freeman

Brown

et al. 2020

Environ. Sci. Technol.

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Metrics & MoreArticle Recommendations * sı Supporting Information ABSTRACT: "Green rust" (GR), a redox-active Fe(II)−Fe(III) layered double hydroxide, is a potential environmentally relevant mineral substrate for arsenic (As) sequestration in reduced, subsurface environments. GR phases have high As uptake capacities at circumneutral pH conditions, but the exact interaction mechanism between the GR phases and As species is still poorly understood. Here, we documented the bonding and interaction mechanisms between GR sulfate and As species [As(III) and As(V)] under anoxic and circumneutral pH conditions through scanning transmission electron microscopy (STEM) coupled with energy-dispersive X-ray (EDX) spectroscopy and combined it with synchrotron-based X-ray total scattering, pair distribution function (PDF) analysis, and As K-edge Xray absorption spectroscopy (XAS). Our highly spatially resolved STEM−EDX data revealed that the preferred adsorption sites of both As(III) and As(V) are at GR crystal edges. Combining this data with differential PDF and XAS allowed us to conclude that As adsorption occurs primarily as bidentate binuclear ( 2 C) innersphere surface complexes. In the As(III)-reacted GR sulfate, no secondary Fe−As phases were observed. However, authigenic parasymplesite (ferrous arsenate nanophase), exhibiting a threadlike morphology, formed in the As(V)-reacted GR sulfate and acts as an additional immobilization pathway for As(V) (∼87% of immobilized As). We demonstrate that only by combining highresolution STEM imaging and EDX mapping with the bulk (differential) PDF and extended X-ray absorption fine structure (EXAFS) data can one truly determine the de facto As binding nature on GR surfaces. More importantly, these new insights into As−GR interaction mechanisms highlight the impact of GR phases on As sequestration in anoxic subsurface environments.

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Intercalation of aromatic sulfonates in ‘green rust’ via ion exchange

Cited by 9 publications

References 27 publications

Controls on Iron Reduction and Biomineralization over Broad Environmental Conditions as Suggested by the FirmicutesOrenia metallireducensStrain Z6

Controls on Iron Reduction and Biomineralization over Broad Environmental Conditions as Suggested by the FirmicutesOrenia metallireducensStrain Z6

Adsorption and Reduction of Arsenate during the Fe²⁺-Induced Transformation of Ferrihydrite

Direct Visualization of Arsenic Binding on Green Rust Sulfate

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Intercalation of aromatic sulfonates in ‘green rust’ via ion exchange

Cited by 9 publications

References 27 publications

Controls on Iron Reduction and Biomineralization over Broad Environmental Conditions as Suggested by the FirmicutesOrenia metallireducensStrain Z6

Controls on Iron Reduction and Biomineralization over Broad Environmental Conditions as Suggested by the FirmicutesOrenia metallireducensStrain Z6

Adsorption and Reduction of Arsenate during the Fe2+-Induced Transformation of Ferrihydrite

Direct Visualization of Arsenic Binding on Green Rust Sulfate

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Adsorption and Reduction of Arsenate during the Fe²⁺-Induced Transformation of Ferrihydrite