Arsenate substitution in natroalunite: A potential medium for arsenic immobilization. Part 1: Synthesis and compositions

Sunyer, Alba; Viñals, J.

doi:10.1016/j.hydromet.2011.05.009

Cited by 19 publications

(9 citation statements)

References 22 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%

“…Arsenical natroalunite precipitation is favoured at (AsO4/TO4)aq < 0.2 at 200 °C. At higher (AsO4/TO4)aq, other arsenate phases such as alarsite (AlAsO4), mansfieldite (AlAsO4•2H2O) and natropharmacoalumite (NaAl4(OH)4(AsO4)3.4H2O) form (Sunyer and Viñals 2011a). At 200 °C, the ratio of (AsO4/TO4) in the precipitated natroalunite was roughly equivalent to 0.5(AsO4/TO4)aq.…”

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%

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

Hudson‐Edwards

2019

American Mineralogist

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“…For example, codisposal of natrojarosite, NaFe 3 (OH) 3 (SO 4 ) 2 , and base-metal sulfide tailings at Kidd Creek, Timmons, Canada (pH 6.5–6.8, Eh = 94–117 mV) caused increased concentrations of Zn, Pb, and As in pore waters associated with the jarosite disposal zone of the tailings pile attributed to enhanced dissolution of jarosites . However, the relative environmental stability of synthetic jarosites over other potential waste mineral hosts such as apatites and pyrochlores has recently made jarosite-type precipitates a potential candidate for long-term disposal of toxic metals such as As, Pb, Bi, Hg, Tl, Sb, Cr, Se, and radioactive isotopes of K, Sr, Th, U, and REE. , Therefore, determining the biogeochemical stability of jarosites is important to evaluate the potential mobility of metals such as As and Pb from disposal sites. To date, research has demonstrated microbial Fe and S reduction in various jarosites including K jarosite, Pb jarosite, and Ag jarosite, yet the biogeochemical stability of jarosites as it relates to As reduction remains to be elucidated. − Theoretically, Fe(III) and As(V) reduction are expected to occur at similar redox potentials but the reduction sequence may vary and will also depend on the crystallinity of the Fe(III) phase .…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Release of Fe and As during the Reductive Dissolution of Pb–As Jarosite by Shewanella putrefaciens CN32

Smeaton

Walshe

Smith

et al. 2012

Environ. Sci. Technol.

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Jarosites are produced during metallurgical processing, on oxidized sulfide deposits, and in acid mine drainage environments. Despite the environmental relevance of jarosites, few studies have examined their biogeochemical stability. This study demonstrates the simultaneous reduction of structural Fe(III) and aqueous As(V) during the dissolution of synthetic Pb-As jarosite (PbFe(3)(SO(4),AsO(4))(2)(OH)(6)) by Shewanella putrefaciens using batch experiments under anaerobic circumneutral conditions. Fe(III) reduction occurred immediately in inoculated samples while As(V) reduction was observed after 72 h. XANES spectra showed As(III) (14.7%) in the solid phase at 168 h coincident with decreased aqueous As(V). At 336 h, XANES spectra and aqueous speciation analysis demonstrated 20.2% and 3.0% of total As was present as As(III) in the solid and aqueous phase, respectively. In contrast, 12.4% of total Fe was present as aqueous Fe(II) and was below the detection limits of XANES in the solid phase. TEM-EDS analysis at 336 h showed secondary precipitates enriched in Fe and O with minor amounts of As and Pb. Based on experimental data and thermodynamic modeling, we suggest that structural Fe(III) reduction was thermodynamically driven while aqueous As(V) reduction was triggered by detoxification induced to offset the high As(V) (328 μM) concentrations released during dissolution.

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“…From the experimental results under the condition of initial pH 2.00 and 25°C, the solubility product [K sp ] and the Gibbs free energies of formation ΔG°f[Na 0.93 (H 3 O) 0.61 Al 2.82 (SO 4 ) 2 (OH) 6 ] had been calculated to be 10 − 81.02±0.33 ∼10 − 81.04±0. 27 and − 4713 ± 2∼− 4714 ± 1 kJ/mol kJ/mol for the natroalunite correspondingly. Few K sp and ΔG°f data for natroalunite have been reported previously in the literature.…”

Section: Determination Of Solubilitymentioning

confidence: 95%

“…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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Arsenate substitution in natroalunite: A potential medium for arsenic immobilization. Part 1: Synthesis and compositions

Cited by 19 publications

References 22 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

Simultaneous Release of Fe and As during the Reductive Dissolution of Pb–As Jarosite by Shewanella putrefaciens CN32

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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