Characterization of Different Solid Particles Transformed from Green Rust in Aqueous Solution — Using XRD, Mössbauer Spectroscopy, and XANES

Inoue, Kazuhide; Sekiguchi, Junji; Fujita, Akira; Shinoda, Kōzō; Kanie, Kiyoshi; Muramatsu, Atsushi; Suzuki, Shigeru; Waseda, Yoshio

doi:10.2355/isijinternational.47.1452

Cited by 11 publications

(8 citation statements)

References 21 publications

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“…The spectra indicate that the copper in GR-Cu was reduced to zero-charge copper because the Cu-K XANES spectrum of GR-Cu is almost the same as that of metallic copper. This is attributed to the fact that the oxygen-reduction potential of the GR suspension was low 20), 21) , thereby copper sulphate ions were reduced under the present condition. The Cu-K XANES spectrum for GR-Cu(ox) shows that the copper in GR-Cu was again oxidized by the H 2 O 2 aqueous solution, although the oxidized copper compound were not identified here.…”

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confidence: 79%

Characterization of Reaction of Green Rust with Foreign Ions using X-ray Absorption Fine Structure

Suzuki

Shinoda

Sato³

et al. 2008

ZAKAEP

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Measurements of X-ray absorption fine structure (XAFS), that is X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), were performed for characterizing the reactions of hydrosulphate green rust (GR) with copper or nickel sulphate ions. Fe K edge XANES spectra showed that a part of Fe(II) in GR2 was oxidized by the addition of copper sulphate ions, while Fe(II) in GR was not oxidized by the addition of nickel sulphate ions. Cu K edge and Ni K edge XANES spectra showed that copper sulphate ions were reduced to zero charge copper in the GR suspension, whereas nickel sulphate ions were not reduced. Radial structural functions for iron obtained from Fe K edge EXAFS spectra indicated that the structure of GR consisted of corner sharing of structural units formed by FeO 6 octahedra. Radial structural functions for copper and nickel also indicated that copper sulphate ions were transformed to metallic copper with the face-centered cubic structure in the GR suspension, whereas the local structure of nickel sulphate ions were unchanged. XANES and EXAFS data of GR oxidized by a H 2 O 2 solution were also investigated for comparison.

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confidence: 79%

Characterization of Reaction of Green Rust with Foreign Ions using X-ray Absorption Fine Structure

Suzuki

Shinoda

Sato³

et al. 2008

ZAKAEP

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“…We have investigated the formation conditions of the iron oxyhydroxides and oxides obtained from GR2(SO 4 2À ) by aerial oxidation. [17][18][19] The results indicate that the transformation of GR2(SO 4 2À ) into the iron oxyhydroxides and oxides is sensitive to oxidation conditions such as reaction temperature and oxidation rate. Furthermore, it is shown that the foreign elements influence the oxidation products that are transformed from GR2(SO 4 2À ).…”

Section: Introductionmentioning

confidence: 95%

Characteristic Behavior of Nickel Ions during Transformation of Green Rust to Ferric Oxyhydroxides in Aqueous Solution

et al. 2008

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X-ray diffraction, transmission electron microscopy, and X-ray absorption spectroscopy were used for characterizing the role of nickel in the transformation of Green Rrust 2(SO 4 2À ) (GR2). GR2(SO 4 2À ) was synthesized from the solution of ferric and ferrous sulfate and that of sodium hydroxide. The suspension containing GR2(SO 4 2À ) with and without nickel was oxidized by passing oxygen gas into the aqueous solution, in which GR2(SO 4 2À ) was transformed into ferric oxyhydroxides. The pH and oxidation reduction potential (ORP) values of the aqueous solution were monitored during the transformation of GR2(SO 4 2À ). In addition, the concentrations of iron and nickel in the solution during the transformation of GR2(SO 4 2À ) were analyzed by using inductively coupled plasma atomic emission spectroscopy. The reaction conditions of the GR2(SO 4 2À ) suspension were found to be strongly influenced by the addition of nickel. The reaction product goethite, which was transformed from GR2(SO 4 2À ), also appeared to be stabilized by the addition of nickel. These results indicate that the species of the solid particles formed in the solution are controlled by the addition of foreign elements.

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“…These stages are not clear in the changes in the ORP and pH values in the GR suspension with 10 mol% copper. According to results obtained in previous works, 11,13) these stages are considered to be corresponding to the formation of two different reaction products like -FeOOH and Fe 3 O 4 in the GR suspensions. Characteristic changes in the ORP values were observed in the stage (a-b) in the GR suspensions with copper.…”

Section: Resultsmentioning

confidence: 99%

“…We have succeeded at synthesizing GR2(SO 4 2À ) by using chemical method and characterize the transformation process of GR2(SO 4 2À ) into the iron oxyhydroxides and oxides by aerial oxidation. [10][11][12][13] The results show that the transformation of GR2(SO 4 2À ) into the iron oxyhydroxides and oxides is sensitive to oxidation conditions such as reaction temperature, oxidation rate and existence of foreign elements.…”

Section: Introductionmentioning

confidence: 93%

“…6,7) Since GR is stable in an aqueous solution of relatively low potential, it is transformed into the iron oxyhydroxides and oxides through the dissolution and precipitation of Fe(II) and Fe(III) ions in an aqueous solution by oxygen gas in air. [8][9][10][11][12][13] Therefore, it is important to elucidate the influence of the addition of an alloying element on the transformation of the iron oxyhydroxides and oxides from the GR in an aqueous solution, in order to understand a role of the element on the transformation of the corrosion products. We have succeeded at synthesizing GR2(SO 4 2À ) by using chemical method and characterize the transformation process of GR2(SO 4 2À ) into the iron oxyhydroxides and oxides by aerial oxidation.…”

Section: Introductionmentioning

confidence: 99%

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Reduction of Copper Ions in Green Rust Suspension and Oxidation of Green Rust Containing Metallic Copper

et al. 2008

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Green rust (GR) consisting both of Fe(II) and Fe(III) was formed in an aqueous solution with a relatively low electrochemical potential. In order to understand both the reduction and oxidation reactions of copper in a GR suspension, the aqueous solution containing Green Rust 2(SO 4 2À ) (GR2(SO 4 2À )) was mixed with a copper sulfate solution and it was subsequently oxidized by passing a gas containing oxygen at room temperature. X-ray diffraction, X-ray absorption spectroscopy, and transmission electron microscopy were used for characterizing the reaction products. Copper ions were found to be reduced to metallic copper in the GR2(SO 4 2À ) suspension, while a part of GR2(SO 4 2À ) was oxidized to be transformed to -FeOOH. The pH and oxidation-reduction potential values of the aqueous solution were measured during the reactions. The importance of the reduction of Cu(II) to metallic copper occurred in the GR2(SO 4 2À ) suspension, and the oxidation processes of the suspension containing metallic copper was suggested as distinct reaction stages. These reaction stages are considered to be attributed to the different electrochemical potential of Cu(II)/Cu(0) and Fe(III)/Fe(II) in solution.

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Characterization of Different Solid Particles Transformed from Green Rust in Aqueous Solution — Using XRD, Mössbauer Spectroscopy, and XANES

Cited by 11 publications

References 21 publications

Characterization of Reaction of Green Rust with Foreign Ions using X-ray Absorption Fine Structure

Characterization of Reaction of Green Rust with Foreign Ions using X-ray Absorption Fine Structure

Characteristic Behavior of Nickel Ions during Transformation of Green Rust to Ferric Oxyhydroxides in Aqueous Solution

Reduction of Copper Ions in Green Rust Suspension and Oxidation of Green Rust Containing Metallic Copper

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