Synthesis, characterization and thermochemistry of synthetic Pb-As, Pb-Cu and Pb-Zn jarosites

Ferenc Lázár Forray, A. M L Smith, A. Navrotsky, Kate Wright, Karen A. Hudson-Edwards, W. E. Dubbin

Research output: Contribution to journalArticle

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Abstract

The enthalpy of formation from the elements of well characterized Pb-As, Pb-Cu, and Pb-Zn synthetic jarosites, corresponding to chemical formulas (H3O)0.68±0.03Pb0.32±0.002Fe2.86±0.14(SO4)1.69±0.08(AsO4)0.31±0.02(OH)5.59±0.28(H2O)0.41±0.02, (H3O)0.67±0.03Pb0.33±0.02Fe2.71±0.14Cu0.25±0.01(SO4)2±0.00(OH)5.96±0.30(H2O)0.04±0.002 and (H3O)0.57±0.03Pb0.43±0.02Fe2.70±0.14Zn0.21±0.01(SO4)2±0.00(OH)5.95±0.30(H2O)0.05±0.002, was measured by high temperature oxide melt solution calorimetry and gave δH°f=-3691.2±8.6kJ/mol, δH°f=-3653.6±8.2kJ/mol, and δH°f=-3669.4±8.4kJ/mol, respectively. Using estimated entropies, the standard Gibbs free energy of formation from elements at 298K δG°f of the three compounds were calculated to be -3164.8±9.1, -3131.4±8.7, and -3153.6±8.9kJ/mol, respectively. Based on these free energies, their logKsp values are -13.94±1.89, -4.38±1.81 and -3.75±1.80, respectively. For this compounds, a log10{Pb2+}-pH diagram is presented. The diagram shows that the formation of Pb-As jarosite may decrease aqueous arsenic and lead concentrations to meet drinking water standards. The new thermodynamic data confirm that transformation of Pb-As jarosite to plumbojarosite is thermodynamically possible.

Original languageEnglish
Pages (from-to)107-119
Number of pages13
JournalGeochimica et Cosmochimica Acta
Volume127
DOIs
Publication statusPublished - 15 Feb 2014
Externally publishedYes

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thermochemistry
Thermochemistry
jarosite
diagram
Gibbs free energy
calorimetry
Arsenic
Calorimetry
enthalpy
Drinking Water
Oxides
Free energy
entropy
Enthalpy
arsenic
Entropy
thermodynamics
drinking water
melt
oxide

Cite this

Forray, Ferenc Lázár ; Smith, A. M L ; Navrotsky, A. ; Wright, Kate ; Hudson-Edwards, Karen A. ; Dubbin, W. E. / Synthesis, characterization and thermochemistry of synthetic Pb-As, Pb-Cu and Pb-Zn jarosites. In: Geochimica et Cosmochimica Acta. 2014 ; Vol. 127. pp. 107-119.
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abstract = "The enthalpy of formation from the elements of well characterized Pb-As, Pb-Cu, and Pb-Zn synthetic jarosites, corresponding to chemical formulas (H3O)0.68±0.03Pb0.32±0.002Fe2.86±0.14(SO4)1.69±0.08(AsO4)0.31±0.02(OH)5.59±0.28(H2O)0.41±0.02, (H3O)0.67±0.03Pb0.33±0.02Fe2.71±0.14Cu0.25±0.01(SO4)2±0.00(OH)5.96±0.30(H2O)0.04±0.002 and (H3O)0.57±0.03Pb0.43±0.02Fe2.70±0.14Zn0.21±0.01(SO4)2±0.00(OH)5.95±0.30(H2O)0.05±0.002, was measured by high temperature oxide melt solution calorimetry and gave δH°f=-3691.2±8.6kJ/mol, δH°f=-3653.6±8.2kJ/mol, and δH°f=-3669.4±8.4kJ/mol, respectively. Using estimated entropies, the standard Gibbs free energy of formation from elements at 298K δG°f of the three compounds were calculated to be -3164.8±9.1, -3131.4±8.7, and -3153.6±8.9kJ/mol, respectively. Based on these free energies, their logKsp values are -13.94±1.89, -4.38±1.81 and -3.75±1.80, respectively. For this compounds, a log10{Pb2+}-pH diagram is presented. The diagram shows that the formation of Pb-As jarosite may decrease aqueous arsenic and lead concentrations to meet drinking water standards. The new thermodynamic data confirm that transformation of Pb-As jarosite to plumbojarosite is thermodynamically possible.",
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Synthesis, characterization and thermochemistry of synthetic Pb-As, Pb-Cu and Pb-Zn jarosites. / Forray, Ferenc Lázár; Smith, A. M L; Navrotsky, A.; Wright, Kate; Hudson-Edwards, Karen A.; Dubbin, W. E.

In: Geochimica et Cosmochimica Acta, Vol. 127, 15.02.2014, p. 107-119.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Synthesis, characterization and thermochemistry of synthetic Pb-As, Pb-Cu and Pb-Zn jarosites

AU - Forray, Ferenc Lázár

AU - Smith, A. M L

AU - Navrotsky, A.

AU - Wright, Kate

AU - Hudson-Edwards, Karen A.

AU - Dubbin, W. E.

PY - 2014/2/15

Y1 - 2014/2/15

N2 - The enthalpy of formation from the elements of well characterized Pb-As, Pb-Cu, and Pb-Zn synthetic jarosites, corresponding to chemical formulas (H3O)0.68±0.03Pb0.32±0.002Fe2.86±0.14(SO4)1.69±0.08(AsO4)0.31±0.02(OH)5.59±0.28(H2O)0.41±0.02, (H3O)0.67±0.03Pb0.33±0.02Fe2.71±0.14Cu0.25±0.01(SO4)2±0.00(OH)5.96±0.30(H2O)0.04±0.002 and (H3O)0.57±0.03Pb0.43±0.02Fe2.70±0.14Zn0.21±0.01(SO4)2±0.00(OH)5.95±0.30(H2O)0.05±0.002, was measured by high temperature oxide melt solution calorimetry and gave δH°f=-3691.2±8.6kJ/mol, δH°f=-3653.6±8.2kJ/mol, and δH°f=-3669.4±8.4kJ/mol, respectively. Using estimated entropies, the standard Gibbs free energy of formation from elements at 298K δG°f of the three compounds were calculated to be -3164.8±9.1, -3131.4±8.7, and -3153.6±8.9kJ/mol, respectively. Based on these free energies, their logKsp values are -13.94±1.89, -4.38±1.81 and -3.75±1.80, respectively. For this compounds, a log10{Pb2+}-pH diagram is presented. The diagram shows that the formation of Pb-As jarosite may decrease aqueous arsenic and lead concentrations to meet drinking water standards. The new thermodynamic data confirm that transformation of Pb-As jarosite to plumbojarosite is thermodynamically possible.

AB - The enthalpy of formation from the elements of well characterized Pb-As, Pb-Cu, and Pb-Zn synthetic jarosites, corresponding to chemical formulas (H3O)0.68±0.03Pb0.32±0.002Fe2.86±0.14(SO4)1.69±0.08(AsO4)0.31±0.02(OH)5.59±0.28(H2O)0.41±0.02, (H3O)0.67±0.03Pb0.33±0.02Fe2.71±0.14Cu0.25±0.01(SO4)2±0.00(OH)5.96±0.30(H2O)0.04±0.002 and (H3O)0.57±0.03Pb0.43±0.02Fe2.70±0.14Zn0.21±0.01(SO4)2±0.00(OH)5.95±0.30(H2O)0.05±0.002, was measured by high temperature oxide melt solution calorimetry and gave δH°f=-3691.2±8.6kJ/mol, δH°f=-3653.6±8.2kJ/mol, and δH°f=-3669.4±8.4kJ/mol, respectively. Using estimated entropies, the standard Gibbs free energy of formation from elements at 298K δG°f of the three compounds were calculated to be -3164.8±9.1, -3131.4±8.7, and -3153.6±8.9kJ/mol, respectively. Based on these free energies, their logKsp values are -13.94±1.89, -4.38±1.81 and -3.75±1.80, respectively. For this compounds, a log10{Pb2+}-pH diagram is presented. The diagram shows that the formation of Pb-As jarosite may decrease aqueous arsenic and lead concentrations to meet drinking water standards. The new thermodynamic data confirm that transformation of Pb-As jarosite to plumbojarosite is thermodynamically possible.

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