Solubilities and Stabilities of Ferric Arsenates

Krause, E.; Ettel, V.

doi:10.1016/b978-0-08-035751-5.50032-5

Cited by 19 publications

(19 citation statements)

References 4 publications

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“…All these vibrational correlations in terms of bond lengths can be verified with existing crystallographic information for scorodite. [4,5,27] In agreement with the present analysis, Baghurst et al [19] reported two similar bands at 3511 (sharp) and 2927 cm −1 (broad) corresponding to hydroxyl stretching vibrations from water molecule in their synthetic scorodite. Previous works [21,31] have reported the OH stretching and H 2 O stretching wavenumbers at 3516 and 3300 cm −1 for natural [27] .…”

Section: Scoroditesupporting

confidence: 79%

Vibrational spectroscopy study of hydrothermally produced scorodite (FeAsO₄·2H₂O), ferric arsenate sub‐hydrate (FAsH; FeAsO₄·0.75H₂O) and basic ferric arsenate sulfate (BFAS; Fe[(AsO₄)_1−x(SO₄)_x(OH)_x]·wH₂O)

Goméz

Assaaoudi

Becze

et al. 2009

J Raman Spectroscopy

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Three crystalline ferric arsenate phases: (1) scorodite; FeAsO 4 ·2H 2 O, (2) ferric arsenate sub-hydrate (FAsH; FeAsO 4 ·0.75H 2 O) and (3) basic ferric arsenate sulfate (BFAS; Fe[(AsO 4 ) 1−x (SO 4 ) x (OH) x ]·wH 2 O) synthesized by hydrothermal precipitation (175-225 • C) from Fe(III)-AsO 4 3− -SO 4 2− solutions have been investigated via Raman and infrared spectroscopies. The spectroscopic nature of these high-temperature Fe(III)-AsO 43− -SO 4 2− phases has not been extensively studied despite their importance to the hydrometallurgical industrial processing of precious metal (Au and Cu) arsenic sulfidic ores. It was found that scorodite, FAsH and BFAS all gave rise to very distinct arsenate, sulfate and hydroxyl vibrations. In scorodite and FAsH, the distribution of the internal arsenate modes was found to be distinct, with the factor effect being more predominant in the crystal system. For the crystallographically unknown BFAS phase, vibrational spectroscopy was used to monitor the arsenate ↔ sulfate solid solution behavior that occurs in this phase where the molecular symmetry of arsenate and sulfate in the crystal structure is reduced from an ideal T d to a distorted T d or C 2 /C 2v symmetry. With the new collected vibrational data of the pure phases, the use of attenuated total reflectance infrared (ATR-IR) spectroscopy was finally extended to investigate the nature of the arsenate in an industrial residue generated by pressure oxidation of a gold ore, where it was found that the arsenate was present in the form of BFAS.

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Section: Scoroditesupporting

confidence: 79%

Vibrational spectroscopy study of hydrothermally produced scorodite (FeAsO₄·2H₂O), ferric arsenate sub‐hydrate (FAsH; FeAsO₄·0.75H₂O) and basic ferric arsenate sulfate (BFAS; Fe[(AsO₄)_1−x(SO₄)_x(OH)_x]·wH₂O)

Goméz

Assaaoudi

Becze

et al. 2009

J Raman Spectroscopy

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“…This compound is not well defined and often termed loosely as amorphous ferric arsenate (Krause and Ettel, 1989) or amorphous scorodite (Langmuir et al, 1999), because it possesses similar bonding structures to crystalline ferric arsenate, i.e. scorodite (FeAsO 4 AE2H 2 O).…”

Section: Effect Of Ph On the Nature Of Adsorbed Arsenatementioning

confidence: 99%

“…scorodite (FeAsO 4 AE2H 2 O). It is an unstable arsenate phase with increasing pH and tends to convert to ferrihydrite (Krause and Ettel, 1989). The poorly crystalline ferric arsenate synthesized in this work was determined to have the formula Fe 1.02 AsO 4 AE2.4H 2 O.…”

Section: Effect Of Ph On the Nature Of Adsorbed Arsenatementioning

confidence: 99%

Infrared spectroscopic and X-ray diffraction characterization of the nature of adsorbed arsenate on ferrihydrite

Jia

Wang

et al. 2007

Geochimica et Cosmochimica Acta

306

122

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“…An attempt was made without success to correlate the arsenic solubility data from the various trivalent metal arsenates to the size of the isovalent cation (ionic radii, solid crystalline form): Al 3+ (0.535 Å; AlAsO 4 ·2H 2 O), Ga 3+ (0.62 Å; GaAsO 4 ·2H 2 O), Fe 3+ (0.64 Å; FeAsO 4 ·2H 2 O), In 3+ (0.80 Å; InAsO 4 ·2H 2 O). [19] In an effort (1) to shed more light into the Raman spectra and molecular structure of these isostructural synthetic compounds and (2) to probe the chemical forces affecting their stability (As release) in aqueous media, the present comparative Raman spectroscopy study was undertaken.…”

Section: Introductionmentioning

confidence: 99%

Raman spectroscopic study of the hydrogen and arsenate bonding environment in isostructural synthetic arsenates of the variscite group—M³⁺ AsO₄·2H₂O (M³⁺ = Fe, Al, In and Ga): implications for arsenic release in water

Goméz

Berre

Assaaoudi

et al. 2011

J Raman Spectroscopy

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The Raman spectra of synthetic compounds equivalent to the variscite group: FeAsO 4 ·2H 2 O AlAsO 4 ·2H 2 O, GaAsO 4 ·2H 2 O, and InAsO 4 ·2H 2 O are reported. In particular, upon comparison of FeAsO 4 ·2H 2 O to AlAsO 4 ·2H 2 O, it is observed that the Type II (weak) H-bond lengths in the latter are slightly longer, which is postulated to affect the stability (As release) in water at pH 5 and 7. Arsenate stretching and bending vibrations were found to be distinct in terms of spectral structure and therefore well suited for fingerprinting. The calculated As-O bond strengths from existing crystallographic data showed no significant variations. The strongest ν 1 (AsO 4 3− ) stretch was used to monitor the As-O bonding interactions in the four As-O-M units, where a shift of 114 cm −1 was observed in the order FeAsO 4 ·2H 2 O (lowest) < InAsO 4 ·2H 2 O < GaAsO 4 ·2H 2 O < AlAsO 4 ·2H 2 O (highest); this order also followed exactly the measured arsenic release of these phases. This shift in ν 1 (AsO 4 3− ) position was rationalized to stem from the differences in the electronegativities of the M 3+ cations. The trends mentioned above were verified and found to also hold for the isostructural phosphate analogues strengite (FePO 4 ·2H 2 O) and variscite (AlPO 4 ·2H 2 O) using published data. Therefore, it is postulated that, as observed with the stability of solution complexes, there may be a correlation between the electronegativity of the M 3+ cation in these isostructural phases and their stability (As or P release) in water.

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Solubilities and Stabilities of Ferric Arsenates

Cited by 19 publications

References 4 publications

Vibrational spectroscopy study of hydrothermally produced scorodite (FeAsO₄·2H₂O), ferric arsenate sub‐hydrate (FAsH; FeAsO₄·0.75H₂O) and basic ferric arsenate sulfate (BFAS; Fe[(AsO₄)_1−x(SO₄)_x(OH)_x]·wH₂O)

Vibrational spectroscopy study of hydrothermally produced scorodite (FeAsO₄·2H₂O), ferric arsenate sub‐hydrate (FAsH; FeAsO₄·0.75H₂O) and basic ferric arsenate sulfate (BFAS; Fe[(AsO₄)_1−x(SO₄)_x(OH)_x]·wH₂O)

Infrared spectroscopic and X-ray diffraction characterization of the nature of adsorbed arsenate on ferrihydrite

Raman spectroscopic study of the hydrogen and arsenate bonding environment in isostructural synthetic arsenates of the variscite group—M³⁺ AsO₄·2H₂O (M³⁺ = Fe, Al, In and Ga): implications for arsenic release in water

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Solubilities and Stabilities of Ferric Arsenates

Cited by 19 publications

References 4 publications

Vibrational spectroscopy study of hydrothermally produced scorodite (FeAsO4·2H2O), ferric arsenate sub‐hydrate (FAsH; FeAsO4·0.75H2O) and basic ferric arsenate sulfate (BFAS; Fe[(AsO4)1−x(SO4)x(OH)x]·wH2O)

Vibrational spectroscopy study of hydrothermally produced scorodite (FeAsO4·2H2O), ferric arsenate sub‐hydrate (FAsH; FeAsO4·0.75H2O) and basic ferric arsenate sulfate (BFAS; Fe[(AsO4)1−x(SO4)x(OH)x]·wH2O)

Infrared spectroscopic and X-ray diffraction characterization of the nature of adsorbed arsenate on ferrihydrite

Raman spectroscopic study of the hydrogen and arsenate bonding environment in isostructural synthetic arsenates of the variscite group—M3+ AsO4·2H2O (M3+ = Fe, Al, In and Ga): implications for arsenic release in water

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Vibrational spectroscopy study of hydrothermally produced scorodite (FeAsO₄·2H₂O), ferric arsenate sub‐hydrate (FAsH; FeAsO₄·0.75H₂O) and basic ferric arsenate sulfate (BFAS; Fe[(AsO₄)_1−x(SO₄)_x(OH)_x]·wH₂O)

Vibrational spectroscopy study of hydrothermally produced scorodite (FeAsO₄·2H₂O), ferric arsenate sub‐hydrate (FAsH; FeAsO₄·0.75H₂O) and basic ferric arsenate sulfate (BFAS; Fe[(AsO₄)_1−x(SO₄)_x(OH)_x]·wH₂O)

Raman spectroscopic study of the hydrogen and arsenate bonding environment in isostructural synthetic arsenates of the variscite group—M³⁺ AsO₄·2H₂O (M³⁺ = Fe, Al, In and Ga): implications for arsenic release in water