Structure and thermodynamics of ferrous, stoichiometric and ferric oxyhydroxycarbonate green rusts; redox flexibility and fougerite mineral

Génin, J.‐M. R.; Ruby, Christian; Upadhyay, Chandan

doi:10.1016/j.solidstatesciences.2006.05.010

Cited by 66 publications

(82 citation statements)

References 24 publications

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“…[5][6][7][8][9][10][11] GR is composed of alternate layers of positively charged hydroxide layers and negatively charged interlayers composed of anions and water molecules; the GR species depends on the negatively charged interlayers and water molecules. 7,8) As GR is observed in a lower layer between the upper layer of the corrosion products and the metallic iron substrate, 3,4) GR is formed in aqueous solutions with a relatively low electrochemical potential. Thus, GR is considered to be transformed into iron oxides and oxyhydroxides through dissolution and precipitation of Fe(II) and Fe(III) ions in an aqueous solution by atmospheric oxygen.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Formation and Oxidation of Green Rust (Cl−) Suspension

et al. 2009

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Green rust (GR) containing both ferrous (Fe(II)) and ferric (Fe(III)) ions is formed in an aqueous solution with a relatively low electrochemical potential. In this study, in order to understand the formation and oxidation of GR, a suspension of GR containing chloride ions (GR(Cl Ϫ )) was synthesized and subsequently oxidized by injecting nitrogen gas containing oxygen under different conditions. X-ray diffraction (XRD) measurements were performed for identifying the solid particles formed under different conditions. The results show that the GR(Cl

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Section: Introductionmentioning

confidence: 99%

Characterization of Formation and Oxidation of Green Rust (Cl−) Suspension

et al. 2009

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“…5b. Green rust products form by gentle oxidation of ferrous phases and are characterised by a crystal structure consisting of stacked brucite-like layers of Fe(OH) 6 octahedrons carrying positive charges and interlayers of anions and water molecules that restore the electroneutrality of the whole structure [41][42][43][44][45][46][47].…”

Section: Surface Characterisationmentioning

confidence: 99%

Current efficiency of individual electrodes in the sodium chlorate process: a pilot plant study

et al. 2017

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Current efficiency in the sodium chlorate process is a key issue in the evaluation of the power consumption. A pilot cell unit for executing the sodium chlorate process was constructed to study the current efficiency of the anode and cathode separately. The effects of sodium dichromate and sodium sulphate concentrations and the electrolyte temperature on the anode and cathode current efficiencies were studied. Corrosion products formed on the mild steel cathodes after their removal from the cell were characterised using X-ray diffraction and infrared spectroscopy. The results show that the cathodic current efficiency increases with increasing dichromate concentrations in the electrolyte until approximately 5 g dm -3 is reached. At this optimum concentration of dichromate, the presence of sulphate ions decreases the cathodic current efficiency. For moderate increases in temperature, the cathodic current efficiency increases, but oxygen evolution is promoted, and the power consumption also increases. Surface characterisation of the electrodes after their exposure to air shows two primary types of behaviour, depending on the process parameters. At low dichromate concentrations, amorphous corrosion layers are formed, while at higher concentrations, reduced forms of iron hydroxides, i.e., ''green rust'', are identified. Although the electrodes were positioned at the open circuit potential for 40 min before their removal from the cell, chromium remains on the cathode surface. This result might explain the corrosion-inhibiting effect of the addition of chromate to the electrolyte. The results from this study can be used to optimise operating procedures in real plants, decrease the energy consumption and minimise the environmental impact of these processes.Electronic supplementary material The online version of this article

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“…In particular, much attention has been paid to the formation of so called "green rusts", which consist of stacked positively charged tri-octahedral sheets of ferrous hydroxide in which some of the Fe(II) has been oxidized to Fe(III). The octahedral sheets are separated by interlayers containing water and chargebalancing anions (see Genin et al, 2006, and references cited therein). At the time of their initial characterization (Bernal et al, 1959;Dasgupta and Mackay, 1959), it was found that green rusts could be characterized by two distinct structures; (1) a rhombohedral form designated as GR-I, which contained simple charge-balancing anions such as OH Earlier work concluded that green rusts occupy a stability field in Eh-pH space defined by neutral to weakly acid pH and moderately reducing (anoxic) conditions (Refait and Genin, 1993;Drissi et al, 1995;Genin et al, 1996Genin et al, , 1998Ruby et al, 2006).…”

Section: Estimation Of the Solubility Product Of Fougeritementioning

confidence: 99%