Beam-induced redox transformation of arsenic during AsK-edge XAS measurements: availability of reducing or oxidizing agents and As speciation
| Autor: | Kim F. Hayes, Hoon Young Jeong, Young-Soo Han, Sung Pil Hyun, Chul Min Chon |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Nuclear and High Energy Physics
X-ray absorption spectroscopy Radiation Absorption spectroscopy Inorganic chemistry chemistry.chemical_element 02 engineering and technology 010501 environmental sciences engineering.material 021001 nanoscience & nanotechnology 01 natural sciences Redox K-edge Mackinawite chemistry Oxidizing agent engineering Arsenic sulfide 0210 nano-technology Instrumentation Arsenic 0105 earth and related environmental sciences |
| Zdroj: | Journal of Synchrotron Radiation. 25:763-770 |
| ISSN: | 1600-5775 |
| DOI: | 10.1107/s1600577518002576 |
| Popis: | During X-ray absorption spectroscopy (XAS) measurements of arsenic (As), beam-induced redox transformation is often observed. In this study, the As species immobilized by poorly crystallized mackinawite (FeS) was assessed for the susceptibility to beam-induced redox reactions as a function of sample properties including the redox state of FeS and the solid-phase As speciation. The beam-induced oxidation of reduced As species was found to be mediated by the atmospheric O2and the oxidation products of FeS [e.g.Fe(III) (oxyhydr)oxides and intermediate sulfurs]. Regardless of the redox state of FeS, both arsenic sulfide and surface-complexed As(III) readily underwent the photo-oxidation upon exposure to the atmospheric O2during XAS measurements. With strict O2exclusion, however, both As(0) and arsenic sulfide were less prone to the photo-oxidation by Fe(III) (oxyhydr)oxides than NaAsO2and/or surface-complexed As(III). In case of unaerated As(V)-reacted FeS samples, surface-complexed As(V) was photocatalytically reduced during XAS measurements, but arsenic sulfide did not undergo the photo-reduction. |
| Databáze: | OpenAIRE |
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