Arsenic immobilization as alunite-type phases: The arsenate substitution in alunite and hydronium alunite

Sunyer, Alba; Currubí, Marta; Viñals, J.

doi:10.1016/j.jhazmat.2013.08.011

Cited by 18 publications

(9 citation statements)

References 24 publications

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“…Arsenate substitution is much higher in alunite and natroalunite (up to 3.61 and 2.80 wt. % As, respectively) formed at pH 1 and 2.8-2.9, respectively, and 200 °C (Sunyer et al 2013;Sunyer and Viñals 2011a). Luo et al (2015) obtained a slightly lower maximum incorporation of arsenate in natroalunite, giving an approximate molar ratio of 11 (AsO4/SO4+AsO4) % at pH 3.00 and 200 °C.…”

Section: Alunite Mineralsmentioning

confidence: 94%

“…To the author's knowledge, no papers have reported the occurrence of natural arsenical members of the alunite family. Arsenate-for-substitution in alunite, natroalunite and hydroniumalunite has been investigated experimentally (Sunyer and Viñals 2011a, b;Sunyer et al 2013;Luo et al 2015). Hydroniumalunite takes only up 1 mole % (AsO4/SO4+AsO4) (0.034 wt.…”

Section: Alunite Mineralsmentioning

confidence: 99%

“…Hydroniumalunite takes only up 1 mole % (AsO4/SO4+AsO4) (0.034 wt. % As), possibly due to the difficulty in substituting protonated H2O-for-OHgroups in the structure due to blocking by H-bridges of the H3O (Sunyer et al 2013). Arsenate substitution is much higher in alunite and natroalunite (up to 3.61 and 2.80 wt.…”

Section: Alunite Mineralsmentioning

confidence: 99%

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Uptake and release of arsenic and antimony in alunite-jarosite and beudantite group minerals

Hudson‐Edwards

2019

American Mineralogist

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Arsenic and antimony are highly toxic to humans, animals and plants. Incorporation in alunite, jarosite and beudantite group minerals can immobilize these elements and restrict their bioavailability in acidic, oxidizing environments. This paper reviews research on the magnitude and mechanisms of incorporation of As and Sb in, and release from, alunite, jarosite and beudantite group minerals in mostly abiotic systems. Arsenate-for-sulfate substitution is observed for all three mineral groups, with the magnitude of incorporation being beudantite (3-8.5 wt. % As) > alunite (3.6 wt. % As) > natroalunite (2.8 wt. %) > jarosite (1.6 wt. % As) > natroalunite (1.5 wt. % As) > hydroniumalunite (0.034 wt. % As). Arsenate substitution is limited by the charge differences between sulfate (-2) and arsenate (-3), deficiencies in B-cations in octahedral sites and for hydroniumalunite, difficulty in substituting protonated H2O-for-OHgroups. Substitution of arsenate causes increases in the c-axis for alunite and natroalunite, and in the c-and a-axes for jarosite. The degree of uptake is dependent on, but limited by, the AsO4/TO4 ratio. Aerobic and abiotic As release from alunite and natroalunite is limited, especially between pH 5 and 8. Release of As is also very limited in As-bearing jarosite, natrojarosite and ammoniumjarosite at pH 8 due to formation of secondary maghemite, goethite, hematite and Fe arsenates that resorb the liberated As.Abiotic reductive dissolution of As-bearing jarosite at pH 4, 5.5 and 7 is likewise restricted by the formation of secondary green rust sulfate, goethite and lepidocrocite that take up the As. Similar processes have been observed for the aerobic dissolution of Pb-As-jarosite (beudantite analogue), with secondary Fe oxyhydroxides resorbing the released As at pH 8. Higher amounts of As are released, however, during microbial-driven jarosite dissolution. Natural jarosite has been found to contain up to 5.9 wt. % Sb 5+ substituting for Fe 3+ in the B-site of the mineral structure. Sb(V) is not released from jarosite at pH 4 during abiotic reductive dissolution, but at pH 5.5 and 7, up to 75% of the mobilized Sb can be structurally incorporated into secondary green rust sulfate, lepidocrocite or goethite. Further research is needed on the co-incorporation of As, Sb and other ions in, and the uptake and release of Sb from, alunite, jarosite and beudantite group minerals, the influence of microbes on these processes and the long-term (>1 year) stability of these minerals.

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Section: Alunite Mineralsmentioning

confidence: 94%

Section: Alunite Mineralsmentioning

confidence: 99%

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Uptake and release of arsenic and antimony in alunite-jarosite and beudantite group minerals

Hudson‐Edwards

2019

American Mineralogist

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“…Other phases with low solubilities are mimetite and mimetitepyromorphite solid solutions (Flis et al, 2011), but they require the presence or addition of lead to the polluted sediments or waste form. Substitution of arsenic into common sulfates, such as jarosite (Savage et al, 2005;Johnston et al, 2012, Forray et al, 2014 or alunite/natroalunite (Vinals et al, 2010, Luo et al, 2015, Sunyer et al, 2016 has also been considered, and may be applicable in systems with low pH and high sulfate concentrations (Welham et al, 2000). Kocourková et al (2011) argued against jarosite/alunite as an arsenic-storage medium, stating that "beudantite and scorodite represent a long-term option for immobilization of arsenic, but arsenic stored in jarosite can be mobilized relatively easily".…”

Section: Document Version Final Published Versionmentioning

confidence: 99%

Thermodynamic properties of mansfieldite (AlAsO₄·2H₂O), angelellite (Fe₄(AsO₄)₂O₃) and kamarizaite (Fe₃(AsO₄)₂(OH)₃·3H₂O)

et al. 2018

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Thermodynamic data for the arsenates of various metals are necessary to calculate their solubilities and to evaluate their potential as arsenic storage media. If some of the less common arsenate minerals have been shown to be less soluble than the currently used options for arsenic disposal (especially scorodite and arsenical iron oxides), they should be further investigated as promising storage media. Furthermore, the health risk associated with arsenic minerals is a function of their solubility and bioavailability, not merely their presence. For all these purposes, solubilities of such minerals need to be known. In this work, a complete set of thermodynamic data has been determined for mansfieldite, AlAsO4·2H2O; angelellite, Fe4(AsO4)2O3; and kamarizaite, Fe3(AsO4)2(OH)3·3H2O, using a combination of high-temperature oxide-melt calorimetry, relaxation calorimetry, solubility measurements, and estimates where possible and appropriate. Several choices for the reference compounds for As for the high-temperature oxide-melt calorimetry were assessed. Scorodite was selected as the best one. The calculated Gibbs free energy of formation (all data in kJ·mol–1) is –1733.4 ± 3.5 for mansfieldite, –2319.2 ± 7.9 for angelellite and –3056.8 ± 8.5 for kamarizaite. The solubility products for the dissolution reactions are –21.4 ± 0.5 for mansfieldite, –43.4 ± 1.5 for angelellite and –50.8 ± 1.6 for kamarizaite. Available, but limited, chemical data for the natural scorodite–mansfieldite solid-solution series hint at a miscibility gap; hence the non-ideal nature of the series. However, no mixing parameters were derived because more data are needed. The solubility of mansfieldite is several orders of magnitude higher than that of scorodite. The solubility of kamarizaite, on the other hand, is comparable to that of scorodite, and kamarizaite even has a small stability field in a pH-pε diagram. It is predicted to form under mildly acidic conditions in acid drainage systems that are not subject to rapid neutralization and sudden strong supersaturation. The solubility of angelellite is high, and the mineral is obviously restricted to unusual environments, such as fumaroles. Its crystallization may be enhanced via its epitaxial relationship with the much more common hematite. The use of the scorodite–mansfieldite solid solution for arsenic disposal, whether the solid solution is ideal or not, is not practical. The difference in solubility products of the two end-members (scorodite and mansfieldite) is so large that almost any system will drive the precipitation of essentially pure scorodite, leaving the aluminium in the aqueous phase.

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“…eir solubility, stability, and mobility depend not only on the solution pH but also on the degree of isomorphous incorporation in the alunite structure [22]. Lately, the replacement of arsenate for sulfate in natroalunite is examined by some scholars [27][28][29][30]. Nevertheless, few works have been carried out on the arsenic incorporation in natroalunite.…”

Section: Introductionmentioning

confidence: 99%

Dissolution and Solubility of the Synthetic Natroalunite and the Arsenic-Incorporated Natroalunite at pH of 2.00–5.60 and 25–45°C

Zhu

Xuan

Liang

et al. 2019

Journal of Chemistry

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Arsenic is very harmful to most living organisms. The solubility data of As-containing compounds are significant in geoscience and environmental science. The arsenic-incorporated natroalunite precipitation has been proposed to eliminate arsenic from water, both for industrial practice and remediation of polluted areas. Unfortunately, only few works have been made on partial arsenic incorporation in natroalunite and the thermodynamic data for natroalunite and arsenic-incorporated natroalunite now are still lacking. Moreover, the dissolution mechanisms of arsenic-incorporated natroalunites have never been studied. In the present work, the dissolution of the synthetic natroalunite [Na0.93(H3O)0.61Al2.82(SO4)2(OH)6] and the synthetic arsenic-incorporated natroalunite [Na0.88(H3O)2.44Al2.35(AsO4)0.38(SO4)1.62(OH)6] at 25°C, 35°C, and 45°C was experimentally examined in HNO3 solution (pH of 2.00 and 4.00) and pure water. The characterizations confirmed that the solids showed no recognizable change after dissolution. All dissolutions underwent a pH variation, which was caused by a great depleting of H3O+/OH− ions, typically at the reaction beginning. The dissolution in H3O+ medium proved to be near-stoichiometric within the short beginning period, and the dissolved Na+, Al3+, SO42−, and AsO43− concentrations were stoichiometric according to the initial solids and then appeared to be nonstoichiometric with the Na/SO4 mole ratios higher and the Al/SO4 and AsO4/SO4 mole ratios lower than the stoichiometry until the experimental end, indicating that the components were released from solid to solution preferentially after the following order: Na+ (H3O+) > SO42− > AsO43− > Al3+. From the experimental results under the condition of initial pH 2.00 and 25°C, the solubility products [Ksp] and the Gibbs free energies of formation [ΔGf°] were calculated to be 10−81.02±0.33∼10−81.04±0.27 and −4713 ± 2 to −4714 ± 1 kJ/mol for the natroalunite and 10−92.30±0.30∼10−92.41±0.37 and −5078 ± 2 to −5079 ± 2 kJ/mol for the arsenic-incorporated natroalunite, respectively. The thermodynamic quantities, ΔG°, ΔH°, ΔS°, and ΔCp°, were determined to be 462303.43 J/K·mol, 122466.83 J/mol, −1140.39 J/K·mol, and 4280.13 J/K·mol for the natroalunite dissolution reaction at initial pH 2.00 and 25°C and to be 526925.48 J/K·mol, 159674.76 J/mol, −1232.38 J/K·mol, and 1061.12 J/K·mol for the dissolution of the arsenic-incorporated natroalunite at initial pH 2.00 and 25°C, respectively.

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Arsenic immobilization as alunite-type phases: The arsenate substitution in alunite and hydronium alunite

Cited by 18 publications

References 24 publications

Uptake and release of arsenic and antimony in alunite-jarosite and beudantite group minerals

Uptake and release of arsenic and antimony in alunite-jarosite and beudantite group minerals

Thermodynamic properties of mansfieldite (AlAsO₄·2H₂O), angelellite (Fe₄(AsO₄)₂O₃) and kamarizaite (Fe₃(AsO₄)₂(OH)₃·3H₂O)

Dissolution and Solubility of the Synthetic Natroalunite and the Arsenic-Incorporated Natroalunite at pH of 2.00–5.60 and 25–45°C

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Arsenic immobilization as alunite-type phases: The arsenate substitution in alunite and hydronium alunite

Cited by 18 publications

References 24 publications

Uptake and release of arsenic and antimony in alunite-jarosite and beudantite group minerals

Uptake and release of arsenic and antimony in alunite-jarosite and beudantite group minerals

Thermodynamic properties of mansfieldite (AlAsO4·2H2O), angelellite (Fe4(AsO4)2O3) and kamarizaite (Fe3(AsO4)2(OH)3·3H2O)

Dissolution and Solubility of the Synthetic Natroalunite and the Arsenic-Incorporated Natroalunite at pH of 2.00–5.60 and 25–45°C

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Thermodynamic properties of mansfieldite (AlAsO₄·2H₂O), angelellite (Fe₄(AsO₄)₂O₃) and kamarizaite (Fe₃(AsO₄)₂(OH)₃·3H₂O)