Electrochemical formation of mackinawite in alkaline sulphide solutions

Shoesmith, D.W.; Bailey, M. G.; Ikeda, B.M.

doi:10.1016/0013-4686(78)80013-9

Cited by 51 publications

(37 citation statements)

References 9 publications

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“…The formation of iron sulfides in H 2 S-saturated solutions using electrochemical techniques is well known. 8,19,21,49,60 Under the conditions used in this work, formation of a black layer of corrosion products on top of the metal surface was already observed after several hours. In Fig.…”

Section: Resultsmentioning

confidence: 75%

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Raman Spectroscopy of Mackinawite FeS in Anodic Iron Sulfide Corrosion Products

Genchev

Erbe

2016

J. Electrochem. Soc.

120

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Raman spectroscopy in a confocal microscope was used to study electrochemically synthesized corrosion products from sour gas experiments. When exposed to oxygen-containing atmosphere, the initial mackinawite FeS corrosion product transformed under laser irradiation to hematite, Fe 2 O 3 . Measurements with a thin water layer on top of the corrosion products prevented the transformation, as drying was prevented. In situ Raman measurements of mackinawite formation avoided the problem of transformation completely. In situ and operando, the initially formed mackinawite showed two Raman peaks in the wavenumber range >180 cm −1 centered around 200-215 cm −1 and 285-300 cm −1 . On an empirical basis, these modes were assigned to a B 1g mode of the iron sublattice and an A 1g mode of the sulfur sublattice, respectively. A comparison with a literature assignment for aged mackinawite suggests that the aging observed involves significant changes in the sulfur sublattice. Corrosion of iron in H 2 S containing solutions is a general problem in crude oil and natural gas production, and is generally referred to as sour corrosion. Aqueous H 2 S solutions promote corrosion of steels, [1][2][3] but the exact nature and mechanisms of corrosion strongly depend on the reaction conditions. 4-7 While the process has been widely investigated for pure iron, [8][9][10][11][12] and carbon steels, [13][14][15][16][17] there is still a lack of understanding of the reaction path and electronic properties of the corrosion products. 18,19The chemistry of the corrosion products formed during H 2 Striggered corrosion is rather complex, as there are many different solids consisting only of iron and sulfur. 20 However, mackinawite has been found to be the initial, 8,21 and probably most important corrosion product, of iron in aqueous sulfide solutions as it was observed in reactions carried out over a wide range of pH and temperature. 11,19,[22][23][24] It possesses a tetragonal, layered crystal structure, [25][26][27] and can be synthesized by precipitation from solutions containing Fe 2+ and S 2− solutions, 28,29 or by reaction of sulfide solution with metallic iron. 19,21,26,30 In the field of microbially induced corrosion, sulfatereducing bacteria are known to transform sulfate compounds into iron sulfides, e.g. mackinawite. [31][32][33][34][35][36] Raman spectroscopy has become an important tool for identification of corrosion products. [37][38][39][40][41][42][43][44][45] Some major problems may still occur due to laser heating, fluorescence, or low sensitivity as a consequence of the small cross-sections of Raman scattering. However, the fact that glass and water are both very weak Raman scatterers makes this technique suitable for in situ measurements in aqueous environments. 46-48The presence of water has an additional positive effect on the process as it decreases the heating from the laser. The use of (in situ and operando) Raman spectroscopy for study corrosion process studies of iron in sulfide rich environments has been already repor...

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Section: Resultsmentioning

confidence: 75%

“…4-7 While the process has been widely investigated for pure iron, [8][9][10][11][12] and carbon steels, [13][14][15][16][17] there is still a lack of understanding of the reaction path and electronic properties of the corrosion products.…”

mentioning

confidence: 99%

Raman Spectroscopy of Mackinawite FeS in Anodic Iron Sulfide Corrosion Products

Genchev

Erbe

2016

J. Electrochem. Soc.

120

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“…In highly alkaline sulfide-containing solutions, competitive adsorption processes involving [OH -] ads and [HS -] ads retard and inhibit the development of an iron oxide passive film, and can instead lead to the precipitation of mackinawite (Fe 1+x S) on the steel surface [43][44][45]. Fig.3 shows two cyclic voltammograms depicting the influence of sulfide on the passivation behaviour of steel in highly alkaline solutions.…”

Section: Binders With a Reducing Internal Environmentmentioning

confidence: 99%

Steel corrosion in reinforced alkali-activated materials

et al. 2017

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The development of alkali-activated materials (AAMs) as an alternative to Portland cement (PC) has seen significant progress in the past decades. However, there still remains significant uncertainty regarding their long term performance when used in steel-reinforced structures. The durability of AAMs in such applications depends strongly on the corrosion behaviour of the embedded steel reinforcement, and the experimental data in the literature are limited and in some cases inconsistent. This letter elucidates the role of the chemistry of AAMs on the mechanisms governing passivation and chloride-induced corrosion of the steel reinforcement, to bring a better understanding of the durability of AAM structures exposed to chloride. The corrosion of the steel reinforcement in AAMs differs significantly from observations in PC; the onset of pitting (or the chloride 'threshold' value) depends strongly on the alkalinity, and the redox environment, of these binders. Classifications or standards used to assess the severity of steel corrosion in PC appear not to be directly applicable to AAMs due to important differences in pore solution chemistry and phase assemblage.

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“…All of these constituents are available and certainly mobile in CM2 chondrites during aqueous alteration. The presence of Cl (Postlethwaite 1967) and S (Shoesmith et al 1978;Vera et al 1986) has the reverse effect and acts to decrease corrosion resistance of Fe,Ni metal. However, the bulk Cl content of CM chondrites is quite low (430 ppm) (Lodders and Fegley 1998), so the corrosive effect of Cl will be minimal, although we note that small amounts of halides have been reported in CM chondrites (Barber 1981).…”

Section: Could Feni Metal Grains Survive Asteroidal Parent Body Altementioning

confidence: 99%

Characterization of micron‐sized Fe,Ni metal grains in fine‐grained rims in the Y‐791198 CM2 carbonaceous chondrite: Implications for asteroidal and preaccretionary models for aqueous alteration

Chizmadia

Schwappach

et al. 2008

Meteorit & Planetary Scien

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available online at Abstract-The presence of apparently unaltered, micron-sized Fe,Ni metal grains, juxtaposed against hydrated fine-grained rim materials in the CM2 chondrite Yamato (Y-) 791198 has been cited as unequivocal evidence of preaccretionary alteration. We have examined the occurrence, composition, and textural characteristics of 60 Fe,Ni metal grains located in fine-grained rims in Y-791198 using scanning electron microscopy (SEM) and electron microprobe analysis. In addition, three metal grains, prepared by focused ion beam (FIB) sample preparation techniques were studied by transmission electron microscopy (TEM). The metal grains are heterogeneously distributed within the rims. Electron microprobe analyses show that all the metal grains are kamacite with minor element contents (P, Cr, and Co) that lie either within or close to the range for other CM2 metal grains. X-ray maps obtained by electron microprobe show S, P, and/or Ca enrichments on the outermost parts of many of the metal grains. Z-contrast STEM imaging of FIB-prepared Fe,Ni metal grains show the presence of a small amount of a lower Z secondary phase on the surface of the grains and within indentations on the grain surfaces. Energy-filtered TEM (EFTEM) compositional mapping shows that these pits are enriched in oxygen and depleted in Fe relative to the metal. These observations are consistent with pitting corrosion of the metal on the edges of the grains and we suggest may be the result of the formation of Fe(OH) 2 , a common oxidation product of Fe metal. The presence of such a layer could have inhibited further alteration of the metal grains. These findings are consistent with alteration by an alkaline fluid as suggested by Zolensky et al. (1989), but the location of this alteration remains unconstrained, because Y-791198 was recovered from Antarctica and therefore may have experienced incipient terrestrial alteration. However, we infer that the extremely low degree of oxidation of the metal is inconsistent with weathering in Antarctica and that alteration in an extraterrestrial environment is more probable. Although the presence of unaltered or incipiently altered metal grains in these fine-grained rims could be interpreted as evidence for preaccretionary alteration, we suggest an alternative model in which metal alteration was inhibited by alkaline fluids on the asteroidal parent body.

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Electrochemical formation of mackinawite in alkaline sulphide solutions

Cited by 51 publications

References 9 publications

Raman Spectroscopy of Mackinawite FeS in Anodic Iron Sulfide Corrosion Products

Raman Spectroscopy of Mackinawite FeS in Anodic Iron Sulfide Corrosion Products

Steel corrosion in reinforced alkali-activated materials

Characterization of micron‐sized Fe,Ni metal grains in fine‐grained rims in the Y‐791198 CM2 carbonaceous chondrite: Implications for asteroidal and preaccretionary models for aqueous alteration

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