Analysis of the iron coatings formed during marcasite and arsenopyrite oxidation at neutral-alkaline conditions
In order to study the nature of the precipitates formed on arsenopyrite and marcasite after reacting with neutral to alkaline solutions, a combination of techniques including Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM-EDS), X-ray Photoelectron Spectroscopy (XPS) and synchrotro...
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| Format: | Article |
| Language: | English |
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Universitat de Barcelona (UB), Geociències Barcelona (Geo3BCN), Institut de Diagnosi Ambiental i Estudis de l'Aigua (IDAEA), Universitat Autònoma de Barcelona (UAB)
2013-12-01
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| Series: | Geologica Acta |
| Subjects: | |
| Online Access: | https://revistes.ub.edu/index.php/GEOACTA/article/view/9737 |
| _version_ | 1827788174825357312 |
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| author | M.P. ASTA R. PÉREZ-LÓPEZ G. ROMÁ V. ILLERA J. CAMA M. COTTE R. TUCOULOU |
| author_facet | M.P. ASTA R. PÉREZ-LÓPEZ G. ROMÁ V. ILLERA J. CAMA M. COTTE R. TUCOULOU |
| author_sort | M.P. ASTA |
| collection | DOAJ |
| description |
In order to study the nature of the precipitates formed on arsenopyrite and marcasite after reacting with neutral to alkaline solutions, a combination of techniques including Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM-EDS), X-ray Photoelectron Spectroscopy (XPS) and synchrotron-based techniques such as micro-X-Ray diffraction (μXRD) and Micro-X-ray Absorption Near Edge Structure (μXANES) have been used. The results showed that the oxidation of marcasite and arsenopyrite under neutral to alkaline conditions leads to the formation of an Fe rich coating which seems to prevent the oxidation of these sulphides. SEM observations confirmed the presence newly-formed phases after the sulphides reaction under the studied conditions. XPS analysis showed that iron, sulphur and arsenic in the case of the arsenopyrite are in oxidized states in the sulphide surfaces. The microscale analysis of the S and Fe speciation performed by μXANES suggested that due to the sulphide oxidation an increase in the oxidation state of those elements took place together with an increase of the sulphate content in the surface layer (grain boundary). Micro-X-ray diffraction results indicated that goethite (α-FeOOH) is the only crystalline newly-formed phase when the reaction occurs at pH 12 whereas at lower pH the products formed on the sulphide surfaces seem to be poorly crystalline and they do not contribute to the diffraction effects in the XRD diagrams.
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| first_indexed | 2024-03-11T17:03:42Z |
| format | Article |
| id | doaj.art-dc3730ecd265456d8740c27ad8cdcad5 |
| institution | Directory Open Access Journal |
| issn | 1696-5728 |
| language | English |
| last_indexed | 2024-03-11T17:03:42Z |
| publishDate | 2013-12-01 |
| publisher | Universitat de Barcelona (UB), Geociències Barcelona (Geo3BCN), Institut de Diagnosi Ambiental i Estudis de l'Aigua (IDAEA), Universitat Autònoma de Barcelona (UAB) |
| record_format | Article |
| series | Geologica Acta |
| spelling | doaj.art-dc3730ecd265456d8740c27ad8cdcad52023-10-20T07:05:33ZengUniversitat de Barcelona (UB), Geociències Barcelona (Geo3BCN), Institut de Diagnosi Ambiental i Estudis de l'Aigua (IDAEA), Universitat Autònoma de Barcelona (UAB)Geologica Acta1696-57282013-12-01114Analysis of the iron coatings formed during marcasite and arsenopyrite oxidation at neutral-alkaline conditionsM.P. ASTA0R. PÉREZ-LÓPEZ1G. ROMÁ2V. ILLERA3J. CAMA4M. COTTE5R. TUCOULOU6Instituto Andaluz de Ciencias de la Tierra (CSIC-Universidad de Granada). Avenida de Las Palmeras 4, Armilla 18100, Granada, Spain. School of Natural Sciences, University of California. 5200 North Lake Road, Merced, CA 95343, USA.Departamento de Geología, Universidad de Huelva. Campus ‘El Carmen’, 21071, Huelva, SpainAmphos 21Passeig de Garcia i Faria, 49-51, 1-1, Barcelona, 08019, SpainSchool of Natural Sciences, University of California. 5200 North Lake Road, Merced, CA 95343, USA.Institute of Environmental Assessment and Water Research (IDAEA), CSICJordi Girona, 18-26, Barcelona 08034, SpainEuropean Synchrotron FacilityBP -220, Grenoble, Cedex, 28043, FranceEuropean Synchrotron FacilityBP -220, Grenoble, Cedex, 28043, France In order to study the nature of the precipitates formed on arsenopyrite and marcasite after reacting with neutral to alkaline solutions, a combination of techniques including Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM-EDS), X-ray Photoelectron Spectroscopy (XPS) and synchrotron-based techniques such as micro-X-Ray diffraction (μXRD) and Micro-X-ray Absorption Near Edge Structure (μXANES) have been used. The results showed that the oxidation of marcasite and arsenopyrite under neutral to alkaline conditions leads to the formation of an Fe rich coating which seems to prevent the oxidation of these sulphides. SEM observations confirmed the presence newly-formed phases after the sulphides reaction under the studied conditions. XPS analysis showed that iron, sulphur and arsenic in the case of the arsenopyrite are in oxidized states in the sulphide surfaces. The microscale analysis of the S and Fe speciation performed by μXANES suggested that due to the sulphide oxidation an increase in the oxidation state of those elements took place together with an increase of the sulphate content in the surface layer (grain boundary). Micro-X-ray diffraction results indicated that goethite (α-FeOOH) is the only crystalline newly-formed phase when the reaction occurs at pH 12 whereas at lower pH the products formed on the sulphide surfaces seem to be poorly crystalline and they do not contribute to the diffraction effects in the XRD diagrams. https://revistes.ub.edu/index.php/GEOACTA/article/view/9737Sulphide oxidation. Iron phases. Arsenopyrite. Marcasite. Neutral-basic pH. |
| spellingShingle | M.P. ASTA R. PÉREZ-LÓPEZ G. ROMÁ V. ILLERA J. CAMA M. COTTE R. TUCOULOU Analysis of the iron coatings formed during marcasite and arsenopyrite oxidation at neutral-alkaline conditions Geologica Acta Sulphide oxidation. Iron phases. Arsenopyrite. Marcasite. Neutral-basic pH. |
| title | Analysis of the iron coatings formed during marcasite and arsenopyrite oxidation at neutral-alkaline conditions |
| title_full | Analysis of the iron coatings formed during marcasite and arsenopyrite oxidation at neutral-alkaline conditions |
| title_fullStr | Analysis of the iron coatings formed during marcasite and arsenopyrite oxidation at neutral-alkaline conditions |
| title_full_unstemmed | Analysis of the iron coatings formed during marcasite and arsenopyrite oxidation at neutral-alkaline conditions |
| title_short | Analysis of the iron coatings formed during marcasite and arsenopyrite oxidation at neutral-alkaline conditions |
| title_sort | analysis of the iron coatings formed during marcasite and arsenopyrite oxidation at neutral alkaline conditions |
| topic | Sulphide oxidation. Iron phases. Arsenopyrite. Marcasite. Neutral-basic pH. |
| url | https://revistes.ub.edu/index.php/GEOACTA/article/view/9737 |
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