The Oxides and Hydroxides of Iron and Their Structural Inter-Relationships

Bernal, J. D.; Dasgupta, D.; Mackay, Alan L.

doi:10.1180/claymin.1959.004.21.02

Cited by 553 publications

(238 citation statements)

References 3 publications

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“…Solo, 31:813-818, 2007 Even though the XRD patterns for the three samples look similar it is possible to understand the influence of Ni on the samples by comparing the lattice parameters for samples prepared with and without the element. Crystallographic parameters (a and c) for sample 1 are similar to those found by Bernal et al (1959) to characterize the structure of GR2 (a = 0.32 nm and c = 1.09 nm), confirming that this sample is pure GR2. For all three samples the cvalues were close to the value 1.097 nm found for pure GR2 and there was no apparent correlation with the presence of Ni in the crystallographic structure.…”

Section: Resultssupporting

confidence: 66%

“…The angular position of the diffraction peaks leads to a series of c spacings close to those described by Bernal et al (1959) which characterize the GR2 structure that is known to be a hexagonal lattice. Table 1 shows the interplanar distances (c) and the dimensions of the unit cell along the a-axis (a) for all samples produced here as calculated from the XRD patterns.…”

Section: Resultsmentioning

confidence: 94%

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Fate of nickel ion in (II-III) hydroxysulphate green rust synthesized by precipitation and coprecipitation

Chaves

Curry

Stone

et al. 2007

Rev. Bras. Ciênc. Solo

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SUMMARYIn order to investigate the efficiency of sulfate green rust (GR2) to remove Ni from solution, GR2 samples were synthesized under controlled laboratory conditions. Some GR2 samples were synthesized from Fe(II) and Fe(III) sulfate salts by precipitation. Other samples were prepared by coprecipitation, of Ni(II), Fe(II) and Fe(III) sulfate salts, i.e., in the presence of Ni. In another sample, Ni(II) sulfate salt was added to pre-formed GR2. After an initial X-ray diffraction (XRD) characterization all samples were exposed to ambient air in order to understand the role of Ni in the transformation of the GR2 samples. XRD was repeated after 45 days. The results showed that Nious GR2 prepared by coprecipitation is isomorphous to Ni-free GR2, i.e. Ni is incorporated into the crystalline structure. Fe(II) was not replaced by Ni(II) in the crystalline structure of GR2 formed prior to exposure to solution-phase Ni. This suggests Ni was adsorbed to the GR2 surface. Sulfate green rust is more efficient in removing Ni from the environment by coprecipitation.Index terms: nickel incorporation, nickel adsorption, X-ray diffraction, isomorphous substitution.(1) Part of the research developed at the University of Arizona, supported by CAPES, during the postdoctoral training period of the first author. RESUMO: ADSORÇÃO DE ÍON NÍQUEL EM (II-III) GREEN RUST HIDROXISULFATO SINTETIZADO POR PRECIPITAÇÃO E CO-PRECIPITAÇÃOCom objetivo de investigar a eficiência do "sulfate green rust" (GR2) na remoção de Ni da solução, amostras de GR2 foram sintetizadas em laboratório sob condições controladas. Algumas amostras de GR2 foram sintetizadas pela precipitação de sais de Fe(II) e de Fe(III); outras amostras, pela co-precipitação de sais de Ni(II), Fe(II) e de Fe(III); e em outras amostras, o sulfato de Ni(II) foi adicionado às amostras GR2 pré-formadas. Após caracterização inicial, por difração de raios X, todas as amostras ficaram expostas ao ar atmosférico durante 45 dias, a fim de se avaliar o papel do Ni na transformação delas. Após esse período, a difração de raios X das amostras foi repetida. Os resultados mostraram que Ni-GR2 preparado por co-precipitação é isomórfico do GR2, estando o íon Ni na estrutura cristalina deste. Fe(II) não foi substituído por Ni(II) na estrutura cristalina de GR2 formado a priori. Talvez o íon Ni tenha sido adsorvido na superfície do GR2. O sulfato "green rust" é eficiente para remover Ni do ambiente somente por co-precipitação.Termos de indexação: incorporação de níquel, adsorção de níquel, difração de raios X, substituição isomórfica.

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Section: Resultssupporting

confidence: 66%

Section: Resultsmentioning

confidence: 94%

Fate of nickel ion in (II-III) hydroxysulphate green rust synthesized by precipitation and coprecipitation

Chaves

Curry

Stone

et al. 2007

Rev. Bras. Ciênc. Solo

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“…According to Bernal et al (1959) green rust I alters topotactically to maghemite by dehydration, or to lepidocrocite by oxidation. The transformation products in the oxidation of green rust I depend on the environmental conditions and pretreatment.…”

Section: Discussionmentioning

confidence: 99%

Influence of Chloride on the Formation of Iron Oxides From Fe(II) Chloride. I. Effect of [Cl]/[Fe] on the Formation of Magnetite

Taylor

1984

Clays and clay miner.

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Abstract--The formation of fine-grained magnetite (t0.1 #m) at pH 7 and 25~ from aeration of Fe(II) chloride solutions is presented. The magnetite converted at 105~ to maghemite with poorly developed superstructure lines. Under the experimental conditions employed, as the initial [C1]/[Fe] ratio was increased from the stoichiometric value of 2, the final product contained increasing amounts oflepidocrocite. The degree ofcrystallinity of this phase, as measured by the width at half height of the 020 X-ray diffraction peak, also increased with this ratio. The hydrolysis rate (base consumption to maintain pH) showed a plateau whose position and extent changed with the initial [C1]/[Fe] ratio. Through this plateau region the Eh decreased to a minimum value the position of which was directly related to the [C1]/[Fe] value. The formation of lepidocrocite rather than magnetite is likely due to the high [C1] where there would be increased difficulty for neighboring OH to condense and eliminate HE0. The formation of Fe-O-Fe bonds in this condensation would be impeded by C1 substitution for OH either in the first formed green rust stage or during its oxidation.

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“…GRs belong to the pyroaurite-class of layered double metal hydroxides, LDHs (Bernal et al, 1959;Brindley and Bish, 1976). These compounds have the ideal composition [FEZ+(6 ~Fe3+x(OH)~2l[(Ax/n).yH~O], where A n.…”

Section: Introductionmentioning

confidence: 99%

Interaction of Synthetic Sulphate “Green Rust” with Phosphate and the Crystallization of Vivianite

Hansen¹

1999

Clays and clay miner.

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Abstract--Because layered Fe(II)Fe(III)-hydroxides (Green rusts, GRs) are anion exchangers, they represent potential orthophosphate sorbents in anoxic soils and sediments. To evaluate this possibility, two types of experiments with synthetic sulphate-interlayered GRs (GRso 4 = Fe2+4Fe3+a(OH)12SO 4 xH20 ) were studied. First, sorption of phosphate in GRso 4 was followed by reacting suspensions of pure GRso ~ synthesized by oxidation of Fe(II) with an excess of Na2HPO4 (pH 9.3). Second the possible incorporation of phosphate in GR during formation by Fe(II)-induced reductive dissolution of phosphate-containing ferrihydrites was examined in systems containing an excess of Fe(lI) (pH 7). With excess phosphate in solution, GRso ~ initially sorbed phosphate in the interlayer producing a basal layer spacing of 1.04 nm, but only --50% of the interlayer sulphate was exchanged with phosphate. This GR slowly transformed to vivianite within months. In the Fe(II)-rich systems, reaction with synthetic ferrihydrites produced GRso 4 similar to that produced by air oxidation. Reaction of Fe(II) with phosphate-containing ferrihydrites initially produced amorphous greenish phosphate containing precipitates which, after 3-4 h, crystallized to GRso 4 and vivianite. In these solutions, stable phosphate-free GRso 4 can form since precipitation of vivianite produced low phosphate activity. Consequently, in both systems GR or amorphous greenish precipitates act as reactive intermediates, but vivianite is the stable end-product limiting phosphate concentration in solution. It is also inferred that Fe(OH) 2 is an unlikely phosphate sorbent in mixed Fe(II)-Fe(III) systems because GR phases are more stable (less soluble) than Fe(OH)2.

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The Oxides and Hydroxides of Iron and Their Structural Inter-Relationships

Abstract: The transformations ia-x the iron oxide-hydroxide system have been interpreted in a rational crystallochemical manner,

Cited by 553 publications

References 3 publications

Fate of nickel ion in (II-III) hydroxysulphate green rust synthesized by precipitation and coprecipitation

Fate of nickel ion in (II-III) hydroxysulphate green rust synthesized by precipitation and coprecipitation

Influence of Chloride on the Formation of Iron Oxides From Fe(II) Chloride. I. Effect of [Cl]/[Fe] on the Formation of Magnetite

Interaction of Synthetic Sulphate “Green Rust” with Phosphate and the Crystallization of Vivianite

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