Mercury forms and their transformation in pyrite under weathering |
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| Authors: | Qingyi Cao Yahui Qian Handong Liang Zhanping Li Siyao Chen Liu Yang Qin Zhan |
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| Institution: | 1. College of Geoscience and Surveying Engineering, China University of Mining and Technology (Beijing), Beijing, China;2. Department of Chemistry, Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Tsinghua University, Beijing, China |
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| Abstract: | Pyrite is considered to be the major carrier of mercury in coal. Here, the chemical characteristics of two natural pyrite samples of different weathering degrees were characterized by time-of-flight secondary ion mass spectrometry (TOF-SIMS). Thermal stability of Hg was also analyzed via temperature programmed desorption experiment (TPD). Characteristic ions such as S−, Fe+, FeS−, and FeS2− were detected on the surface of fresh pyrite. The release temperature of Hg ranged between 180°C and 300°C, and the characteristic peak of black HgS was recorded. In addition, abundant Fe2O3−, FeSO−, SO4−, and HSO4− were detected on the surface of weathered pyrite, and the release temperature of Hg therein was mainly distributed at 260°C to 380°C and 520°C to 600°C, corresponding to the characteristic peaks of red HgS and HgSO4, respectively. The results show that pyrite is acidified during weathering and that Hg forms in pyrite are transformed from the original state (HgS) to HgSO4. |
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| Keywords: | mercury forms pyrite temperature programmed desorption TOF-SIMS weathering |
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