Investigation of radionuclide~(63)Ni(Ⅱ) sequestration mechanisms on mordenite by batch and EXAFS spectroscopy study

查看全文 作　　者：YANG ShiTong,SHENG GuoDong,GUO ZhiQiang,TAN XiaoLi,XU JinZhang & WANG XiangKe Key Laboratory of Novel Thin Film Solar Cells,Institute of Plasma Physics,Chinese Academy of Sciences,Hefei 230031,China

出　　处：《Science China Chemistry》索引2012年第55卷第4期,共11页

基　　金：supported by the National Natural Science Foundation of China (20907055,20971126 & 21077107);the National Basic Research Program of China (2011CB933700);the Knowledge Innovation Program of CAS and Special Foundation for High-level Waste Disposal (2007-840) 摘　　要：The sorption behavior and microscopic sequestration mechanisms of radionuclide 63Ni(II) on mordenite as a function of aging time,ionic strength,initial 63Ni(Ⅱ) concentrations,solid content and coexistent electrolyte ions were investigated by the com-bination of batch and EXAFS techniques.Macroscopic experiment results show that the sorption of 63Ni(Ⅱ) is dependent on ionic strength at pH<7,and independent of ionic strength at pH>7.The sorption percentage of 63Ni(Ⅱ) on mordenite increases with increasing solid content,while the sorption capacity decreases as solid content increases.The presence of different elec-trolyte ions can enhance or inhibit the sorption of Ni(II) on mordenite in various degrees.EXAFS analysis results of the sam-ples under three different ionic strengths suggest that the retained 63Ni(Ⅱ) in these samples exists in an octahedral environment with six water ligands.In the initial period of rapid uptake,the sorption of 63Ni(Ⅱ) is dominated by the formation of in-ner-sphere surface complexes.As aging time increases,63Ni(Ⅱ) sequestration behavior tends to be mainly controlled by the formation of Ni phyllosilicate co-precipitates and/or Ni(OH)2(s) precipitates.Results for the second shell fit of the sample pre-pared at an initial 63Ni(Ⅱ) concentration of 100 mg/L indicate the possible formation of Ni polynuclear surface complexes.Both the macroscopic sorption data and the molecular level evidence of 63Ni(Ⅱ) surface speciation at the mordenite/water in-terfaces should be factored into better predictions of the mobility and bioavailability of 63Ni(Ⅱ) in environment mediums. 关键词：EXAFS技术丝光沸石放射性核素机制 NI(OH)2 吸附行为离子强度扣押

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Investigation of radionuclide~(63)Ni(Ⅱ) sequestration mechanisms on mordenite by batch and EXAFS spectroscopy study

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