The oxidation of carbonate green rust into ferric phases:solid-state reaction or transformation via solution

Legrand, Ludovic; Mazérolles, L.; Chaussé, A.

doi:10.1016/j.gca.2004.02.019

Cited by 108 publications

(97 citation statements)

References 46 publications

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“…The reaction rates are the limiting factors for the formation of iron oxides like hematite and magnetite from solution. Precipitation of ferrihydrite from Fe 2+ /Fe 3+ bearing solutions is favored over the formation of goethite (FeO(OH) or hematite [18]. A wide range of literature shows that ferrihydrite is the most common iron phase in natural soils, soil water and surface water [7,16,18].…”

Section: Resultsmentioning

confidence: 99%

“…Precipitation of ferrihydrite from Fe 2+ /Fe 3+ bearing solutions is favored over the formation of goethite (FeO(OH) or hematite [18]. A wide range of literature shows that ferrihydrite is the most common iron phase in natural soils, soil water and surface water [7,16,18]. Ferrihydrite transforms slowly into goethite and is therefore the most common but metastable iron phase [19,20].…”

Section: Resultsmentioning

confidence: 99%

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Stability of iron minerals in Icelandic peat areas and transport of heavy metals and nutrients across oxidation and salinity gradients – a modelling approach

Linke

Gíslason

2018

Energy Procedia

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District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand -outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. AbstractThe storage of carbon, metals and nutrients in peat lands at high latitude is sensitive to climate-and land usage changes. This work shows that the thermodynamically most stable iron phases in Icelandic peat areas, like hematite or magnetite do not form, but rather the metastable ferrihydrite, which forms in abundance. Model calculations suggest that this ferrihydrite is able to adsorb high concentrations of natural derived heavy metals (Pb, As, Cr, Cu) and nutrients (P). If this ferrihydrite comes in contact with the oceans, these elements will be released through ferrihydrite-seawater interaction. This process may have significant effects to the chemistry of the near shore environments if ferrihydrite transport to the oceans increase due to future increased flooding and sea level rise.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Stability of iron minerals in Icelandic peat areas and transport of heavy metals and nutrients across oxidation and salinity gradients – a modelling approach

Linke

Gíslason

2018

Energy Procedia

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“…Peaks at 890 and 796 cm -1 are also observed that may arise from goethite [40]. In the trials at 3 g dm -3 , no lepidocrocite could be observed; rather, an oxidised form of green rust, exGR-Fe(III) [41], with broad peaks at 655 and 470 cm -1 , was found.…”

Section: Surface Characterisationmentioning

confidence: 91%

“…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%

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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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Oxidation of Dodecanoate Intercalated Iron(II)–Iron(III) Layered Double Hydroxide to Form 2D Iron(III) (Hydr)oxide Layers

et al. 2013

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A planar trioctahedral iron(II)-iron(III) hydroxide (green rust, GR) intercalated with dodecanoate (GR C12 ) has been oxidized by dioxygen to produce the corresponding planar iron(III) (hydr)oxide. The formulae of GR C12 and the final iron(III) product (oxGR C12 ) were determined to be Fe II 2.00 Fe III 1.00 (OH) 5.31 (C 12 H 23 O 2 ) 0.66 (SO 4 ) 0.51 and Fe III 3 O 2.18 -(OH) 3.13 (C 12 H 23 O 2 ) 0.56 (SO 4 ) 0.47 , respectively. oxGR C12 has the same planar layer structure as GR C12 , as revealed by identical powder X-ray diffraction patterns. The electrostatic interactions between the interlayer dodecanoate (C12) anions and the iron hydroxide planar layer were preserved during the oxidation, as shown by FTIR spectroscopy. The high positive charge in the hydroxide layer produced by the oxidation of iron(II) to iron(III) is partially compensated by the deprotonation of hydroxy groups, as shown by X-ray [a]

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The oxidation of carbonate green rust into ferric phases:solid-state reaction or transformation via solution

Cited by 108 publications

References 46 publications

Stability of iron minerals in Icelandic peat areas and transport of heavy metals and nutrients across oxidation and salinity gradients – a modelling approach

Stability of iron minerals in Icelandic peat areas and transport of heavy metals and nutrients across oxidation and salinity gradients – a modelling approach

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

Oxidation of Dodecanoate Intercalated Iron(II)–Iron(III) Layered Double Hydroxide to Form 2D Iron(III) (Hydr)oxide Layers

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