An occurrence of akaganéite (β-FeOOH ˙ C1) in Recent oxidized carbonate concretions, Norfolk, England

Pye, Kenneth

doi:10.1180/minmag.1988.052.364.12

Cited by 16 publications

(10 citation statements)

References 10 publications

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“…Sediment located 0.1-0.4 m below the seawater-seabed interface has been demonstrated to concentrate Cl´ions from 18.986 g Cl´¨L´1 in the seawater to 20-24 g Cl´¨L´1 when akaganeite has formed as a digenetic product [86]. The observations in Figure D1 are therefore consistent with observations made in the natural environment.…”

Section: D1 Salinity Concentration Associated With Zvi Corrosion Prsupporting

confidence: 81%

ZVI (Fe0) Desalination: Stability of Product Water

Antia¹

2016

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A batch-operated ZVI (zero valent iron) desalination reactor will be able to partially desalinate water. This water can be stored in an impoundment, reservoir or tank, prior to use for irrigation. Commercial development of this technology requires assurance that the partially-desalinated product water will not resalinate, while it is in storage. This study has used direct ion analyses to confirm that the product water from a gas-pressured ZVI desalination reactor maintains a stable salinity in storage over a period of 1-2.5 years. Two-point-three-litre samples of the feed water (2-10.68 g (Na + + Cl´)¨L´1) and product water (0.1-5.02 g (Na + + Cl´)¨L´1) from 21 trials were placed in storage at ambient (non-isothermal) temperatures (which fluctuated between´10 and 25˝C), for a period of 1-2.5 years. The ion concentrations (Na + and Cl´) of the stored feed water and product water were then reanalysed. The ion analyses of the stored water samples demonstrated: (i) that the product water salinity (Na + and Cl´) remains unchanged in storage; and (ii) the Na:Cl molar ratios can be lower in the product water than the feed water. The significance of the results is discussed in terms of the various potential desalination routes. These trial data are supplemented with the results from 122 trials to demonstrate that: (i) reactivity does not decline with successive batches; (ii) the process is catalytic; and (iii) the process involves a number of steps.

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Section: D1 Salinity Concentration Associated With Zvi Corrosion Prsupporting

confidence: 81%

ZVI (Fe0) Desalination: Stability of Product Water

Antia¹

2016

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“…Most of the iron sulphide is X-ray amorphous, acid-volatile and easily oxidized in air. Reworked concretions exposed on creek beds and the intertidal flats contain varying amounts of goethite, akaganeite, amorphous iron oxyhydroxides and gypsum (Pye, 1988).…”

Section: Composition Of the Concretionsmentioning

confidence: 99%

Formation of siderite‐Mg‐calcite‐iron sulphide concretions in intertidal marsh and sandflat sediments, north Norfolk, England

Pye

Dickson²,

Schiavon³

et al. 1990

Sedimentology

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176

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Concretions cemented mainly by siderite, Mg‐calcite and iron monosulphide are common in late Holocene marsh and sandflat sediments on parts of the north Norfolk coast. Field experiments have shown that the concretions are actively forming in reduced sediments in which sulphate‐reducing bacteria are active. δ13C values ranging from −3 to −11·8% (mean −5·9%0) suggest that the carbonate in the concretions is derived partly from marine sources and partly from microbial degradation of organic matter. δ18O values ranged from −6·4% to + 0·8% (mean −1·0%) suggesting that carbonate precipitated in porewaters ranging from pure sea water to‐sea water diluted with meteoric water. Chemical analysis of porewaters showed no evidence of significant sulphate depletion at the depth of concretion formation. Some concretions have formed around fragments of wood or metal, but others contain no apparent nucleus. In field experiments siderite, FeS and Mg‐calcite were precipitated around several different nuclei within a period of six months. We suggest that siderite may form wherever the rate of iron reduction exceeds the rate of sulphate reduction, such that insufficient dissolved sulphide is available to precipitate all the available dissolved ferrous iron.

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“…Solution pH and Cl − concentration are the dominant factors controlling akaganeite formation in terrestrial environments (Cornell & Schwertmann, ). Natural akaganeite usually forms through oxidation of Fe(II) and metallic Fe to Fe(III) followed by Fe(III) hydrolysis to akaganeite under chloride‐rich acidic conditions in hot brines, marine environments, oxidized sulfide‐rich sediments, carbonate concretions, meteorites, volcanic rocks, and plumes (Bibi et al, ; Buchwald & Clarke, ; Font et al, ; Johnston, ; Mackay, ; Morris et al, ; Pye, ). Synthetic akaganeite forms through forced hydrolysis of 0.1–2 M Fe(III) chloride solutions at room temperature (RT) or at elevated temperatures (40–120 °C) under acidic (initial pH < 2) conditions (Zhao et al, ).…”

Section: Introductionmentioning

confidence: 99%

Effect of Solution pH and Chloride Concentration on Akaganeite Precipitation: Implications for Akaganeite Formation on Mars

et al. 2018

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Akaganeite, a chloride-bearing Fe(III) (hydr)oxide, has been reported on Mars in Yellowknife Bay in Gale crater by X-ray diffraction (XRD), in Robert Sharp crater by Compact Reconnaissance Imaging Spectrometer for Mars, and possibly at the Gusev crater and Meridiani Planum by combined Mössbauer and bulk chemistry analyses. Because formation conditions remain unknown, we investigated akaganeite precipitation as a function of solution pH and chloride concentration. Akaganeite was synthesized through hydrolysis of Fe(III) perchlorate in the presence of 0.02, 0.05, and 0.1 M chloride and at initial solution pH of 1.6, 4, 6, and 8 at 90°C. Mineralogy of the precipitated Fe(III) (hydr)oxides was characterized by XRD, infrared spectroscopy, and Mössbauer spectroscopy. Total chloride and perchlorate contents were determined by ion chromatography. XRD revealed that akaganeite formed alone or in mixtures with ferrihydrite, hematite, and/or goethite at initial pH 1.6 with 0.02, 0.05, and 0.1 M Cl À and at initial pH from 4 to 8 with 0.05 and 0.1 M Cl À . Infrared analysis showed that akaganeite bands at~2 and~2.45 μm were sensitive to amount of akaganeite, total chloride content, and presence of other Fe(III) (hydr)oxides. The results indicate that akaganeite in Yellowknife Bay in Gale crater likely formed under acidic to alkaline (1.6 < pH < 8) oxidizing conditions in solutions containing >0.05 M Cl À by the dissolution of basaltic minerals. Akaganeite in Robert Sharp crater may have formed in acidic (pH < 4) solutions with~0.1 M Cl À through oxidative dissolution of Fe(II) sulfides and/or acidic oxidizing dissolution of basalts.Plain Language Summary Akaganeite, a chloride-bearing Fe(III) (hydr)oxide, has been reported in several locations (e.g., Gale and Robert Sharp craters) on Mars, but formation conditions are unknown. The objective of this work was to investigate formation of akaganeite at variable pH and dissolved chloride concentrations and to characterize the past aqueous conditions in the locations where akaganeite was detected on Mars. We found that akaganeite on Mars could form under substantially different environmental conditions. Akaganeite in Yellowknife Bay likely formed under acidic to alkaline moderately saline conditions by the dissolution of basaltic minerals. Akaganeite in Robert Sharp crater may have formed in acidic saline solutions through oxidative dissolution of Fe(II) sulfides and/or acidic oxidizing dissolution of basalts.

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An occurrence of akaganéite (β-FeOOH ˙ C1) in Recent oxidized carbonate concretions, Norfolk, England

Cited by 16 publications

References 10 publications

ZVI (Fe0) Desalination: Stability of Product Water

ZVI (Fe0) Desalination: Stability of Product Water

Formation of siderite‐Mg‐calcite‐iron sulphide concretions in intertidal marsh and sandflat sediments, north Norfolk, England

Effect of Solution pH and Chloride Concentration on Akaganeite Precipitation: Implications for Akaganeite Formation on Mars

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