Reactivity of surface chemical states on fractured pyrite

Schaufuß, Andrea G; Nesbitt, H.W.; Kartio, I.; Laajalehto, K.; Bancroft, G.M.; Szargan, R.

doi:10.1016/s0039-6028(98)00355-0

Cited by 186 publications

(96 citation statements)

References 16 publications

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“…The Fe 2p spectra show a narrow peak at 707.2 eV which is recognized as a Fe 2p 3/2 signal from low-spin Fe(II) in the pyrite lattice. A second Fe 2p 3/2 contribution found at a higher binding energy (BE) is mainly due to a multiplet structure (four maxima plus satellite) with a highest intensity at ∼709.8 eV from surface Fe(III) oxyhydroxides [17][18][19][20][21][22]. The presence of this Fe 2p feature is in agreement with the O 1 s spectra containing an O 2− contribution (530.4 eV), which reduces in spectra taken with increasing excitation energy and, therefore, probing depth.…”

Section: Haxpesmentioning

confidence: 99%

“…Additional minor lines are ascribed to monosulfide (161.8 eV), and polysulfide (163.5 eV) and satellite at about 164.5 eV [17][18][19][20][21][22][23][24] and slightly vary with the excitation photon energy. The VB spectra are dominated by non-bonding Fe 3d 6 orbital states in the vicinity of 2 eV below the Fermi level [5][6][7].…”

Section: Haxpesmentioning

confidence: 99%

“…It is known from X-ray photoelectron spectroscopy (XPS) and other surface-sensitive techniques [2][3][4][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] that iron can be easily released from the lattice of these compounds, leaving non-equilibrium metal-deficient surface layers. The resulting surface sulfur enrichment is generally modest for oxidation-resistant pyrite, with intrinsic (fractured) pyrite surfaces possibly even being S-deficient [2][3][4][5][6][17][18][19][20][21][22][23][24][25][26]. In contrast, the metal depleted layer incorporates di-and polysulfide species and low-spin Fe(II) and can be as thick as several micrometers at pyrrhotite reacted in acidic solutions under certain conditions [27][28][29][30][31][32][33][34]…”

Section: Introductionmentioning

confidence: 99%

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Hard X-ray photoelectron and X-ray absorption spectroscopy characterization of oxidized surfaces of iron sulfides

Mikhlin

Tomashevich

Vorobyev

et al. 2016

Applied Surface Science

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a b s t r a c tHard X-ray photoelectron spectroscopy (HAXPES) using an excitation energy range of 2 keV to 6 keV in combination with Fe K-and S K-edge XANES, measured simultaneously in total electron (TEY) and partial fluorescence yield (PFY) modes, have been applied to study near-surface regions of natural polycrystalline pyrite FeS 2 and pyrrhotite Fe 1−x S before and after etching treatments in an acidic ferric chloride solution. It was found that the following near-surface regions are formed owing to the preferential release of iron from oxidized metal sulfide lattices: (i) a thin, no more than 1-4 nm in depth, outer layer containing polysulfide species, (ii) a layer exhibiting less pronounced stoichiometry deviations and low, if any, concentrations of polysulfide, the composition and dimensions of which vary for pyrite and pyrrhotite and depend on the chemical treatment, and (iii) an extended almost stoichiometric underlayer yielding modified TEY XANES spectra, probably, due to a higher content of defects. We suggest that the extended layered structure should heavily affect the near-surface electronic properties, and processes involving the surface and interfacial charge transfer.

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Section: Haxpesmentioning

confidence: 99%

Section: Haxpesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hard X-ray photoelectron and X-ray absorption spectroscopy characterization of oxidized surfaces of iron sulfides

Mikhlin

Tomashevich

Vorobyev

et al. 2016

Applied Surface Science

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“…These could be attributed to the atmospheric/partial oxidation of the bulk rock during excavation, transport and storage prior to sampling, which induced the formation of more soluble secondary phases especially on the surfaces of exposed pyrite grains. Pyrite oxidation starts rapidly upon exposure to the atmosphere, commencing with the oxidation of S 2-species (Schaufuss et al, 1998). Oxidation is further enhanced in the presence of water or moisture that could strip reaction products on the pyrite surface exposing "fresh" sites for further oxidation.…”

Section: Soluble Arsenic and Lead-bearing Phases Calcite Dissolutionmentioning

confidence: 99%

“…Oxidation is further enhanced in the presence of water or moisture that could strip reaction products on the pyrite surface exposing "fresh" sites for further oxidation. Atmospheric pyrite oxidation leads to the formation of Fe-sulfates, Fe oxyhydroxides/oxides, which are soluble especially under acidic conditions (De Donato et al, 1993;Schaufuss et al, 1998;Todd et al, 2003). Dissolution of these soluble products of atmospheric/partial oxidation of pyrite enhanced the mobility of Pb but not As (Table 8).…”

Section: Soluble Arsenic and Lead-bearing Phases Calcite Dissolutionmentioning

confidence: 99%

The roles of pyrite and calcite in the mobilization of arsenic and lead from hydrothermally altered rocks excavated in Hokkaido, Japan

Tabelin¹,

Igarashi²,

Tamoto³

et al. 2012

Journal of Geochemical Exploration

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This paper describes the enrichment of hydrothermally altered volcanic and sedimentary rocks with arsenic (As) and lead (Pb), and the effects of pyrite and calcite on the mobilities and release mechanisms of these toxic elements under oxic and anoxic conditions. Enrichment of the altered rock with As and Pb predominantly occurred in precipitated pyrite grains and not on the alumino-silicate minerals making up the matrix of the rock. Arsenic was incorporated in pyrite grains formed during alteration in both volcanic and sedimentary rocks, but Pb was only found in the pyrite grains of the volcanic rock samples. When in contact with water, altered volcanic rocks had acidic pH while altered sedimentary rocks had alkaline pH. The mobilities of both As and Pb from the altered rocks were enhanced at acidic and alkaline pH and a minimum was observed in the circumneutral pH under both oxic and anoxic conditions. The absence of O 2 retarded the oxidation of pyrite most notably in the alkaline region but not in the acidic and circumneutral pH. The absence of CO 2 increased the pH of samples with significant calcite content but did not affect those containing substantial amounts of pyrite. Increasing the CO 2 also had insignificant effect on the concentrations of As and Pb in the leachate. The mechanisms controlling the mobilization of As and Pb from these rocks like dissolution of soluble secondary minerals, pyrite oxidation and adsorption were all related to pyrite while the pH of the rock when in contact with water was controlled by pyrite and calcite. Thus, excavated waste rocks that have been altered can be grouped based on the relative abundance of pyrite and calcite and their pH when in contact with water.

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XPS of sulphide mineral surfaces: metal-deficient, polysulphides, defects and elemental sulphur

Smart

Skinner

Gerson

1999

Surf. Interface Anal.

361

187

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This paper reviews evidence for the assignments of components of the S 2p XPS spectra from sulphide mineral surfaces under different conditions of preparation, oxidation and reaction. Evidence from other techniques confirming assignment of high‐binding‐energy S 2p components to metal‐deficient sulphide surfaces, polysulphides, elemental sulphur and electronic defect structures is considered for specific cases. Reliable assignment of S 2p3/2 components at 163.6–164.0 eV to elemental sulphur Sn0 can be confirmed by evaporative loss at 295 K and/or observation of S–S bonding by x‐ray absorption fine structure (XAFS), x‐ray diffraction or vibrational spectroscopy. Assignment to polysulphides Sn2− at 162.0–163.6 eV requires confirmation of S–S bonding by XAFS or vibrational spectroscopy. Metal‐deficient lattices can be represented as electronic defects (e.g. vacancies) or restructured surface phases confirmed by diffraction or XAFS evidence. High‐binding‐energy S 2p3/2 components can also result from Cu(I) substitution into ZnS with associated oxidation of sulphur as electronic defect sites without S–S bonding, metal deficiency or restructuring. This assignment is confirmed by XAFS evidence. Copyright © 1999 John Wiley & Sons, Ltd.

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Reactivity of surface chemical states on fractured pyrite

Cited by 186 publications

References 16 publications

Hard X-ray photoelectron and X-ray absorption spectroscopy characterization of oxidized surfaces of iron sulfides

Hard X-ray photoelectron and X-ray absorption spectroscopy characterization of oxidized surfaces of iron sulfides

The roles of pyrite and calcite in the mobilization of arsenic and lead from hydrothermally altered rocks excavated in Hokkaido, Japan

XPS of sulphide mineral surfaces: metal-deficient, polysulphides, defects and elemental sulphur

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