Structural Iron in Smectites

Stucki, Joseph W.

doi:10.1007/978-94-009-4007-9_17

Cited by 95 publications

(80 citation statements)

References 119 publications

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“…(Yan and Stucki, 1999). The reduction of structural Fe also increases the surface-charge density of the clay (Stucki, 1988;Stucki and Tessier, 1991;Gates et al, 1993;Yan and Stucki, 1999), causing the Fe(II)-bearing smectites to acquire a strong nucleophilic character that facilitates the transformation of chlorinated alkanes. The high concentration of H20 relative to that of 5CA, and the fact that smectite surfaces hydrate (Yan et al, 10 ...... 1996b, 1996cYan and Stucki, 1999), suggest that H20 molecules mediate the hydrogen bridging and the long-range interactions between 5CA and the clay surface ("outer sphere complex"; Wilkins, 1991).…”

Section: Resultsmentioning

confidence: 99%

Adsorption Kinetics of Pentachloroethane by Iron-Bearing Smectites

Cervini-Silva

Stucki

et al. 2000

Clays and clay miner.

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Abstract--The oxidation state of structural Fe greatly alters surface chemistry, which may have a large influence on clay-organic interactions. The effect of structural-iron oxidation state on chlorinated hydrocarbons at the clay-water interface was examined. Pentachloroethane (5CA) was reacted with oxidized, reduced, and reoxidized forms of three different smectites: montmorillonite, ferruginous smectite, and nontronite in aqueous suspension under controlled-atmosphere conditions. Pentachloroethane was found to adsorb at different rates for the three smectites. A series of 5CA-adsorption rate constants in the presence of these clays showed a strong correlation with the Fe(II) content of the clay (r 2 = 0.98). The clay surface behaves as a Br0nsted base and promotes 5CA dehydrochlorination. The adsorption kinetics at the clay-water interface were described by the formation of a precursor complex prior to 5CA dehydrochlorination.

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Section: Resultsmentioning

confidence: 99%

Adsorption Kinetics of Pentachloroethane by Iron-Bearing Smectites

Cervini-Silva

Stucki

et al. 2000

Clays and clay miner.

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“…Microbial Fe(III) or Mn(IV) reduction has been proposed as the source of siderite or rhodochrosite in aquatic sediments (92,285 (74). The reduction of Fe(III) in clays might be directly coupled to the oxidation of organic matter, but the actual reduction mechanisms are unknown (74,296). Fe(III)-reducing microorganisms can readily reduce the Fe(III) oxide coatings on the exterior of clay particles (193,195).…”

Section: Generation Of Iron and Manganese Mineralsmentioning

confidence: 99%

Dissimilatory Fe(III) and Mn(IV) Reduction

Lovley

Holmes

Nevin

2004

Advances in Microbial Physiology

1,484

1,061

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“…The extent and the rate that smectite-illite minerals affect these environmental processes are largely determined by their physical and chemical properties, which are correlated with the oxidation state of Fe in their structures (1,2). Although the oxidation state of Fe in smectite-illite minerals can be altered by abiotic reactions, the role that microbes play in cycling Fe oxidation states has become increasingly recognized.…”

Section: Introductionmentioning

confidence: 99%

Microbial Reduction of Structural Fe(III) in Illite and Goethite

Dong

Kukkadapu

Fredrickson

et al. 2003

Environ. Sci. Technol.

136

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Microbial reduction of Fe(III) in illite was studied to evaluate the possibility of microbial utilization of Fe(III) in sedimentary clays and to determine the effects of bioreduction on clay composition and structure. A subsurface bacterium (Shewanella putrefaciens CN32) and illite separates (<0.2 µm) from St. Peter Formation sandstone in Ogle County, IL, were used in laboratory experiments. Illite suspensions buffered at pH 7 with bicarbonate were inoculated with CN32 and provided with H 2 as an electron donor. In selected treatments, anthraquinone-2,6-disulfonate (AQDS), was included as an electron shuttle to facilitate the bioreduction. Fe(II) production in inoculated treatments was determined by extraction with 0.5 N HCl and compared to uninoculated controls to establish the extent of biological reduction. The resulting solids were characterized by Mo ¨ssbauer spectroscopy and scanning and transmission electron microscopy (SEM and TEM). The characterization of the starting illite material revealed that it contained a minor component of goethite (R-FeOOH) in addition to fibrous illite. The starting material (both goethite and illite) contained 6% (w/ w) total Fe, and 82% of the total Fe was Fe(III). Approximately 30% of total Fe was associated with goethite. At the end of a 30-day incubation, residual goethite and illite remained. The extent of reduction was much greater in the presence of AQDS (25%) than in its absence (0%). Modeling of Mo ¨ssbauer spectra of the bioreduced material indicated that both goethite and illite were reduced but to a different extent. Additionally, TEM evidence suggested that there was a dramatic change in illite morphology upon bioreduction from fibrous needles to plates. The ability of bacteria to utilize Fe(III) in illite has important implications for microbial functions and survival mechanisms, as well as many geological processes, in the subsurface.

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Structural Iron in Smectites

Cited by 95 publications

References 119 publications

Adsorption Kinetics of Pentachloroethane by Iron-Bearing Smectites

Adsorption Kinetics of Pentachloroethane by Iron-Bearing Smectites

Dissimilatory Fe(III) and Mn(IV) Reduction

Microbial Reduction of Structural Fe(III) in Illite and Goethite

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