Chemical composition and Gibbs standard free energy of formation of Fe(II)-Fe(III) hydroxysulphate green rust and Fe(II) hydroxide

Refait, Philippe; Bon, Chris Yeajoon; Simon, Larry J.; Bourrié, Guilhem; Trolard, Fabienne; Bessière, J.; Génin, J.‐M. R.

doi:10.1180/000985599546280

Cited by 77 publications

(49 citation statements)

References 30 publications

(37 reference statements)

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“…The spectrum was acquired on a narrower velocity range in order to precise the hyperfine parameters and two quadrupole doublets, D 1 and D 2 , can be fitted. Such doublets are also found in GR(Cl − ) [1] and GR(CO 2À 3 ) [6], whereas only one (D 1 ) is found in GR(SO 2À 4 ) [2]. The D 1 /D 2 area ratio is about two.…”

Section: E H and Ph Vs Time Curvesmentioning

confidence: 94%

“…Spectra were computer-fitted with Lorentzian shape lines and errors on the Mössbauer parameters determination were estimated by analysing three samples. Measurements were performed at 15 K, a temperature allowing us to discriminate GRs from Fe(OH) 2 and Fe(III) oxyhydroxides [1,2]. The GR obtained was also analysed by Raman spectroscopy by using a Jobin Yvon spectrometer (LabRAM HR), with a resolution of about 2 cm −1 .…”

Section: Methodsmentioning

confidence: 99%

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Synthesis and characterisation of the Fe(II–III) hydroxy-formate green rust

et al. 2006

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A new methodology was envisioned in order to prepare green rust compounds build on organic anions that could intervene in microbiologically influenced corrosion processes of iron and steel. The formate ion was chosen as an example. The formation of rust was simulated by the oxidation of aqueous suspensions of Fe(OH) 2 precipitated from Fe(II) lactate and sodium hydroxide, in the presence of sodium formate to promote the formation of the corresponding green rust. The evolution of the precipitate with time was followed by transmission Mössbauer spectroscopy at 15 K. It was observed that the initial hydroxide was transformed into a new GR compound. Its spectrum is composed of three quadrupole doublets, D 1 (δ=1.28 mm s −1 , Δ=2.75 mm s −1 ) and D 2 (δ=1.28 mm s −1 , Δ= 2.48 mm s −1 ) that correspond to Fe(II) and D 3 (δ=0.49 mm s −1 , Δ=0.37 mm s −1 ) that corresponds to Fe(III). The relative area of D 3 , close to the proportion of Fe(III) in the GR, was found at 28.5±1.5% (∼2/7). Raman spectroscopy confirmed that the intermediate compound was a Fe(II-III) hydroxy-formate, GR(HCOO − ).

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Section: E H and Ph Vs Time Curvesmentioning

confidence: 94%

Section: Methodsmentioning

confidence: 99%

Synthesis and characterisation of the Fe(II–III) hydroxy-formate green rust

et al. 2006

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“…The Eh, by contrast, displays a much earlier, steep drop (up to 500 mV in minutes, whereas the pH hardly changes) followed by a slow decline. When superimposed on the Pourbaix diagram (30)(31)(32) in Fig. 5C, we see that the system moves from the region of ferrous ion stability through the GR2 zone into the white-rust domain and then back into the GR2 zone, tracking the appearance of a white-rust band and then the obscuring zone and finally the gray precipitate.…”

Section: Physicsmentioning

confidence: 96%

Tubular precipitation and redox gradients on a bubbling template

Stone

Goldstein²

2004

Proc. Natl. Acad. Sci. U.S.A.

101

102

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Tubular structures created by precipitation abound in nature, from chimneys at hydrothermal vents to soda straws in caves. Their formation is controlled by chemical gradients within which precipitation occurs, defining a surface that templates the growing structure. We report a self-organized periodic templating mechanism producing tubular structures electrochemically in iron-ammonium-sulfate solutions; iron oxides precipitate on the surface of bubbles that linger at the tube rim and then detach, leaving behind a ring of material. The acid-base and redox gradients spontaneously generated by diffusion of ammonia from the bubble into solution organize radial compositional layering within the tube wall, a mechanism studied on a larger scale by complex Liesegang patterns of iron oxides formed as ammonia diffuses through a gel containing FeSO 4. When magnetite forms within the wall, a tube may grow curved in an external magnetic field. Connections with free-boundary problems in speleothem formation are emphasized.

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“…Materials of this class are known as "green rusts", are easily prepared, and are well established as intermediates in the corrosion of metallic Fe under low oxygen conditions (Hansen, 1989;Refait et al, 1998;Loyaux-Lawniczak et al, 1999;Refait et al, 1999). These materials are effective traps for selenium as selenate, and react effectively with chromate, reducing it to Cr(III) as hydroxide or, possibly, as a component of modified LDH (Loyaux-Lawniczak et al, 1999).…”

Section: Chemistry Of Layered Double Hydroxidesmentioning

confidence: 99%

Potential applications of nanostructured materials in nuclear waste management.

Braterman

Phol²,

et al. 2003

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This report summarizes the results obtained from a Laboratory Directed Research & Development (LDRD) project entitled "Investigation of Potential Applications of SelfAssembled Nanostructured Materials in Nuclear Waste Management". The objectives of this project are to (1) provide a mechanistic understanding of the control of nanometerscale structures on the ion sorption capability of materials and (2) develop appropriate engineering approaches to improving material properties based on such an understanding. 4 The project has been focused on two types of nanostructured materials: self-assembled mesoporous materials and layered double hydroxides. The major results are summarized below:• Acid-base titration experiments were performed on both mesoporous alumina and alumina particles under various ionic strengths. Under the same chemical conditions, the surface charge per mass on mesoporous alumina was as much as 45 times higher than that on alumina particles. This difference cannot be fully explained by the surface area difference between the two materials. The titration data have demonstrated that the nano-scale confinement has a significant effect, most likely via the overlap of the electric double layer (EDL), on ion sorption onto mesopore surfaces. This effect cannot be adequately modeled by existing surface complexation models, which were developed mostly for an unconfined solid-water interface.• As the pore size is reduced to a few nanometers, the difference between surface acidity constants (∆pK = pK 2 -pK 1 ) decreases, giving rise to a higher surface charge density on a nanopore surface than that on an unconfined mineral-water interface. The change in surface acidity constants results in a shift of ion sorption edges and enhances ion sorption on nanopore surfaces. Also, the water activity in a nanopore is greatly reduced, thus increasing the tendency for inner sphere complexation and mineral precipitation. All these effects combine to preferentially enrich trace elements in nanopores. This enrichment mechanism has a significant implication to many fundamental geochemical issues such as the irreversibility of ion sorption/desorption and the bioavailability of subsurface contaminants. The discovery of this mechanism provides a scientific basis for engineering high-performance ion adsorbents for nuclear waste management.• Layered double hydroxides (LDH) have shown a great promise for removing anionic contaminants. The anion sorption coefficients (K d ) have been measured for both activated and non-activated Mg-Al LDH materials. The activated material has a much higher anion sorption coefficient than the non-activated one, indicating that calcination can significantly improve anion sorption capacity of LDH. Sorption isotherms for Re and Se on the activated LDH material roughly follow the Freundlich isotherm, indicating the existence of various sorption sites with different sorption capabilities. Anions tend to first sorb on the external surface sites. As the anion concentration or the ionic strength ...

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Chemical composition and Gibbs standard free energy of formation of Fe(II)-Fe(III) hydroxysulphate green rust and Fe(II) hydroxide

Cited by 77 publications

References 30 publications

Synthesis and characterisation of the Fe(II–III) hydroxy-formate green rust

Synthesis and characterisation of the Fe(II–III) hydroxy-formate green rust

Tubular precipitation and redox gradients on a bubbling template

Potential applications of nanostructured materials in nuclear waste management.

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