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Antimony speciation in saline hydrothermal fluids: A combined X-ray absorption fine structure spectroscopy and solubility studyстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
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Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
- Авторы: Pokrovski Gleb S., Borisova Anastassia Yu, Roux Jacques, Hazemann Jean-Louis, Petdang Alain, Tella Marie, Testemale Denis
- Журнал: Geochimica et Cosmochimica Acta
- Том: 70
- Номер: 16
- Год издания: 2006
- Издательство: Pergamon Press Ltd.
- Местоположение издательства: United Kingdom
- Первая страница: 4196
- Последняя страница: 4214
- DOI: 10.1016/j.gca.2006.06.1549
- Аннотация: Solubility of senarmontite (Sb2O3, cubic) in pure water and NaCl-HCl aqueous solutions, and local atomic structure around antimony in these fluids were characterized using in situ X-ray absorption fine structure (XAFS) spectroscopy at temperatures to 450 degrees C and pressures to 600 bars. These experiments were performed using a new X-ray cell which allows simultaneous measurement of the absolute concentration of the absorbing element in the fluid, and atomic environment around the absorber. Results show that aqueous Sb(III) speciation is dominated by the Sb(OH)(3)degrees complex in pure water, mixed Sb-hydroxide-chloride complexes in acidic NaCl-HCl solutions (2 m NaCl-0.1 m HCl), and by Sb-chloride species in concentrated HCl solutions (3.5 m HCl). Interatomic Sb-O and Sb-Cl distances in these complexes range from 1.96 to 1.97 angstrom and from 2.37 to 2.47 angstrom, respectively. These structural data, together with senarmontite solubility determined from XAFS spectra, were complemented by batch-reactor measurements of senarmontite and stibnite (Sb2S3, rhombic) solubilities over a wide range of HCl and NaCl concentrations from 300 to 400 degrees C. Analysis of the whole dataset shows that Sb(III) speciation in high-temperature moderately acid (pH > 2-3) Cl-rich fluids is dominated by mixed hydroxy-chloride species like Sb(OH)(2)Cl degrees and Sb(OH)(3)Cl-, but other species containing two or three Cl atoms appear at higher acidities and moderate temperatures (<= 300 degrees C). Calculations using stability constants retrieved in this study indicate that mixed hydroxy-chloride complexes control antimony transport in saline high-temperature ore fluids at acidic conditions. Such species allow for a more effective Sb partitioning into the vapor phase during boiling and vapor-brine separation processes occurring in magmatic-hydrothermal systems. Antimony hydroxychloride complexes are however minor in the neutral low- to moderate-temperature solutions (<= 250-300 degrees C) typical of Sb deposits formation; the antimony speciation in these systems is dominated by Sb(OH)(3) and potentially Sb-sulfide species. (c) 2006 Elsevier Inc. All rights reserved.
- Добавил в систему: Борисова Анастасия Юрьевна