Aluminous goethite: A m�ssbauer study

Fysh, Stuart A.; Clark, Paul

doi:10.1007/bf00308241

Cited by 91 publications

(42 citation statements)

References 27 publications

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“…The Al-goethite was crystalline with MCD 111 of ϳ24 nm. Aluminum substitution causes a reduction in crystallite size and unit cell dimensions (Norrish and Taylor, 1961;Thiel, 1963;Bigham et al, 1978;Fysh and Clark, 1982). The decrease in d 111 spacing and MCD 111 (Fig.…”

Section: Properties Of the Sediment Goethite Fractionmentioning

confidence: 99%

“…Lowering the measurement temperature reduces relaxation ef- 2919 Bacterial reduction of Al-goethite fects. Fysh and Clark (1982) proposed that the relaxation effects for Al-goethite were negligible at 4.2 K. Murad and Schwertmann (1983), in contrast, argued that the particle size effects were not completely removed at 4.2 K. Both Fysh and Clark, and Murad and Schwertmann proposed equations to calculate the Al content of synthetic Al-goethites from spectra collected at 4.2 K. Murad and Schwertmann further suggested that crystallinity information (surface area or MCD) data were essential for the calculation of Al content.…”

Section: Properties Of the Sediment Goethite Fractionmentioning

confidence: 99%

“…Lorentzian modeling of the 4.2 spectrum was performed to allow comparison with the work of Fysh and Clark (1982) and Murad and Schwertmann (1983). The B hf values obtained for the inner (49.55 T) and outer sextets (53.02 T) were typical of Al-goethite and hematite.…”

Section: Properties Of the Sediment Goethite Fractionmentioning

confidence: 99%

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Dissimilatory bacterial reduction of Al-substituted goethite in subsurface sediments

Kukkadapu

Zachara

Smith

et al. 2001

Geochimica et Cosmochimica Acta

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Abstract-The microbiologic reduction of a 0.2 to 2.0 m size fraction of an Atlantic coastal plain sediment (Eatontown) was investigated using a dissimilatory Fe(III)-reducing bacterium (Shewanella putrefaciens, strain CN32) to evaluate mineralogic controls on the rate and extent of Fe(III) reduction and the resulting distribution of biogenic Fe(II). Mössbauer spectroscopy and X-ray diffraction (XRD) were used to show that the sedimentary Fe(III) oxide was Al-substituted goethite (13-17% Al) that existed as 1-to 5-m aggregates of indistinct morphology. Bioreduction experiments were performed in two buffers [HCO 3 Ϫ ; 1,4-piperazinediethansulfonic acid (PIPES)] both without and with 2,6-anthraquinone disulfonate (AQDS) as an electron shuttle. The production of biogenic Fe(II) and the distribution of Al (aqueous and sorbed) were followed over time, as was the formation of Fe(II) biominerals and physical/chemical changes to the goethite.The extent of reduction was comparable in both buffers. The reducibility (rate and extent) was enhanced by AQDS; 9% of dithionite-citrate-bicarbonate (DCB) extractable Fe(III) was reduced without AQDS whereas 15% was reduced in the presence of AQDS. XRD and Mössbauer spectroscopy were used to monitor the disposition of biogenic Fe(II) and changes to the Al-goethite. Fe(II) biomineralization was not evident by XRD. Biomineralization was observed by Mössbauer when sorbed Fe(II) concentrations exceeded a threshold value. The biomineralization products displayed Mössbauer spectra consistent with siderite FeCO 3 (HCO 3 Ϫ buffer only) and green rust . Adsorption of biogenic Fe(II) to accessory mineral phases (e.g., kaolinite) and bacterial surfaces appeared to limit biomineralization. Al evolved during reduction was sorbed, and extractable Al increased with reduction. XRD analysis indicated that neither crystallite size or the Al content of the goethite was affected by bacterial reduction, i.e., Al release was congruent with Fe(II).

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Section: Properties Of the Sediment Goethite Fractionmentioning

confidence: 99%

Section: Properties Of the Sediment Goethite Fractionmentioning

confidence: 99%

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Dissimilatory bacterial reduction of Al-substituted goethite in subsurface sediments

Kukkadapu

Zachara

Smith

et al. 2001

Geochimica et Cosmochimica Acta

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“…It accounts for 34% of the total spectral area, and is most likely due to hematite. Its hyperfine field is too large to be due to goethite (H3o0.K = 383 kOe, Fysh and Clark, 1982a), and the negative quadrupole splitting eliminates the possibility of maghemite (H300,~ = 500 kOe, A = +0.01 mm/sec, Longworth and Tite, 1977). The hyperfine field of hematite at 300~ is 517 kOe, and its quadrupole splitting is -0.21 mm/sec (Fysh and Clark, 1982b of a decreased hyperfine field for hematite at 300~ have been discussed elsewhere .…”

Section: K Spectramentioning

confidence: 99%

“…Known masses of the cleaned kaolin (sample K3) and pure goethite (U4.2OK = 0.69 + 0.02, Fysh and Clark, 1982a) of known Fe content were mixed, and the 4.2~ spectrum of this absorber is shown in Figure 5. The hyperfine splitting of the pure goethite is 505 kOe, so that the small spectral contribution arising from the surface iron could not be resolved from that of the goethite.…”

Section: Recoil-free Fraction Determinationmentioning

confidence: 99%

Mössbauer Effect Studies of Iron in Kaolin. II. Surface Iron

Fysh

Cashion

Clark

1983

Clays and clay miner.

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Abstract--57Fe M6ssbauer spectra have been used to interpret the effects of different cleaning processes on the iron mineralogy of a Weipa, Australia, kaolin. A magnetically separated fraction contained 28% of its iron as hematite likely of secondary origin. An initial centrifugal size separation was shown to give an improved final product, and oxalic acid was found to be more efficient at removing Fe from the kaolinite surface than dithionite bleach. The MSssbauer spectra clearly show that beneficiation steps which give a substantial increase in kaolin brightness result in only minor changes in the clay iron mineralogy. Similar results were also obtained for two commercially available kaolins.

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⁵⁷Fe Mössbauer Spectroscopy In The Investigation of The Precipitation of Iron Oxides

Musić¹,

Ristić²,

Krehula³

2013

Mössbauer Spectroscopy

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Aluminous goethite: A m�ssbauer study

Cited by 91 publications

References 27 publications

Dissimilatory bacterial reduction of Al-substituted goethite in subsurface sediments

Dissimilatory bacterial reduction of Al-substituted goethite in subsurface sediments

Mössbauer Effect Studies of Iron in Kaolin. II. Surface Iron

⁵⁷Fe Mössbauer Spectroscopy In The Investigation of The Precipitation of Iron Oxides

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Aluminous goethite: A m�ssbauer study

Cited by 91 publications

References 27 publications

Dissimilatory bacterial reduction of Al-substituted goethite in subsurface sediments

Dissimilatory bacterial reduction of Al-substituted goethite in subsurface sediments

Mössbauer Effect Studies of Iron in Kaolin. II. Surface Iron

57Fe Mössbauer Spectroscopy In The Investigation of The Precipitation of Iron Oxides

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⁵⁷Fe Mössbauer Spectroscopy In The Investigation of The Precipitation of Iron Oxides