Galvanic effect of pyrite on arsenic release from arsenopyrite dissolution in oxygen-depleted and oxygen-saturated circumneutral solutions
| Autor: | Virginia S.T. Ciminelli, Claudia L. Caldeira, Maria Sylvia Silva Dantas, Erico T.F. Freitas, D. Majuste, P.M. Ferreira |
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| Rok vydání: | 2021 |
| Předmět: |
Environmental Engineering
Sulfide Health Toxicology and Mutagenesis Inorganic chemistry 0211 other engineering and technologies chemistry.chemical_element 02 engineering and technology 010501 environmental sciences engineering.material 01 natural sciences Ferrihydrite medicine Environmental Chemistry Waste Management and Disposal Dissolution Arsenic 0105 earth and related environmental sciences chemistry.chemical_classification Arsenopyrite 021110 strategic defence & security studies Pollution Sulfur chemistry visual_art engineering visual_art.visual_art_medium Ferric Pyrite medicine.drug |
| Zdroj: | Journal of Hazardous Materials. 412:125236 |
| ISSN: | 0304-3894 |
| Popis: | Arsenopyrite (FeAsS), the most common arsenic-bearing mineral, is usually found associated with pyrite (FeS2) in gold mining tailings. This work examined the galvanic effect of FeS2 on As release from FeAsS oxidation in circumneutral media under oxygen-depleted and oxygen-saturated conditions. The oxidation experiments were conducted with a flow-through reactor in the absence of FeS2 particles and in the presence of different contents of this sulfide. The results indicated that the permanent, physical contact between FeAsS and FeS2 particles causes an increase in the accumulated As release, mainly under O2-saturated conditions. At 30% wt. FeS2, the increases relatively to FeS2-free conditions were 82% and 117% in O2-depleted and O2-saturated solutions, respectively. At steady-state, the As release rates increased from (4.9 ± 0.5)× 10−4 µmol m−2 s−1 (0% wt. FeS2) to (1.1–1.9)× 10−3 µmol m−2 s−1 (5–30% wt. FeS2) under O2-saturated conditions. Analysis of FeAsS samples after oxidation revealed oxidized particles partially or entirely covered by precipitates with different sizes, shapes and compositions (e.g., As−S−bearing ferrihydrite, elemental sulfur, and As−O phases). A fine (3–4 nm thick) amorphous layer of S−As−bearing ferric oxy-hydroxide was also identified on oxidized FeAsS, with Fe(III) and As(III) species. |
| Databáze: | OpenAIRE |
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