Uranium speciation in coal bottom ash investigated via X-ray absorption fine structure and X-ray photoelectron spectra |
| |
Authors: | Yinglong Sun Menxin Wu Lirong Zheng Bangda Wang Yi Wang |
| |
Affiliation: | National Meteorological Center, China Meteorological Administration, Beijing 100081, China;Key Laboratory for Solid Waste Management and Environment Safety, Ministry of Education of China, Tsinghua University, Beijing 100084, China,National Meteorological Center, China Meteorological Administration, Beijing 100081, China,Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039, China,Key Laboratory for Solid Waste Management and Environment Safety, Ministry of Education of China, Tsinghua University, Beijing 100084, China and Key Laboratory for Solid Waste Management and Environment Safety, Ministry of Education of China, Tsinghua University, Beijing 100084, China |
| |
Abstract: | Similar to chromium contamination, the environmental contamination caused by uranium in radioactive coal bottom ash (CBA) is primarily dependent on the chemical speciation of uranium. However, the relationship between uranium speciation and environmental contamination has not been adequately studied. To determine the relationship between uranium speciation and environmental contamination, X-ray absorption fine structure (XAFS) and X-ray photoelectron spectra (XPS) analyses were performed to determine the uranium speciation in CBA exposed to different chemical environments and simulated natural environments. The leachability of the different forms of uranium in the CBA was studied via a simulated acid rain leaching experiment, and the results showed that 57.0% of the total uranium was leached out as U(VI). The results of a linear combination fit (LCF) of the X-ray absorption near edge structure (XANES) spectrum revealed that in the raw CBA, the uranium mainly occurred as U3O8 (71.8%). However, in the iron-rich particles, the uranium mainly occurred as UO2 (91.9%) after magnetic separation. Magnetite is a ubiquitous ferrous-bearing oxide, and it was effective for the sorption of U(IV). The result of FeSO4 leaching experiment indicated that 96.57% of total uranium was reduced from U(VI) to U(IV) when infiltrated with the FeSO4 solution for 6 months. This result clearly demonstrated the changes in chemical valence of uranium in the coal ash and provided a conceptual principle for preventing uranium migration from ash to the surrounding soil and plants. |
| |
Keywords: | Coal bottom ash Uranium speciation XAFS Uranium migratio |
|
| 点击此处可从《环境科学学报(英文版)》浏览原始摘要信息 |
|
点击此处可从《环境科学学报(英文版)》下载全文 |
|