Uranium speciation in coal bottom ash investigated via X-ray absorption fine structure and X-ray photoelectron spectra

作     者：Yinglong Sun Menxin Wu Lirong Zheng Bangda Wang Yi Wang 

作者机构：National Meteorological CenterChina Meteorological Administration Key Laboratory for Solid Waste Management and Environment Safety Ministry of Education of China Tsinghua University Beijing Synchrotron Radiation Facility Institute of High Energy Physics Chinese Academy of Sciences 

出 版 物：《Journal of Environmental Sciences》 (环境科学学报（英文版）)

年 卷 期：2018年第30卷第12期

页      面：88-94页

核心收录：

学科分类：083002[工学-环境工程] 0830[工学-环境科学与工程（可授工学、理学、农学学位）] 07[理学] 08[工学] 09[农学] 0903[农学-农业资源与环境] 0713[理学-生态学] 

基　　金：supported by the Talent Support Fund of Tsinghua University(No.413405001) 

主　　题：Coal bottom ash Uranium speciation XAFS Uranium migration 

摘      要：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 U_3O_8（71.8%）. However, in the iron-rich particles, the uranium mainly occurred as UO_2（91.9%） after magnetic separation. Magnetite is a ubiquitous ferrousbearing oxide, and it was effective for the sorption of U（IV）. The result of FeSO_4 leaching experiment indicated that 96.57% of total uranium was reduced from U（VI） to U（IV） when infiltrated with the FeSO_4 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.