New insight into Cm(III) interaction with kaolinite - Influence of mineral dissolution
New insight into Cm(III) interaction with kaolinite - Influence of mineral dissolution
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DOI：
10.1016/j.gca.2012.09.032
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发表时间：
2012-12-15
影响因子：
5
通讯作者：
Geckeis, H.
中科院分区：
文献类型：
--
作者：
Huittinen, N.;Rabung, Th.;Geckeis, H.
采用时间分辨激光荧光光谱法（TRLFS）研究了碱性条件下天然高岭石（St.奥斯特尔，UK）悬浮液中Cm（III）的形态分布。在整个研究过程中，光谱研究在氩气气氛（O-2 < 1 ppm）下进行，使用恒定的铥浓度、离子强度和矿物质含量分别为2 x 10（-7）M、1 mM NaClO 4和0.25 g/L。高岭石矿物溶解对三价锕系元素形态的影响进行了研究，在过饱和实验中，过量的铝和/或硅被添加到碱性高岭石悬浮液。只有硅的加入被发现影响的实验条件下表明在高岭石环境中形成的居里-硅酸盐复合物的居里配体场。在添加10（-3）M硅但没有固相用于结合铥的实验中，在pH 10下仅可检测到水解物质Cm（OH）（2）（+）。因此，胶体硅酸盐物种的形成，用于附件的锔可以被排除在外，在碱性高岭石环境中观察到的物种可以被分配到一个三元高岭石/curium/硅酸盐复合物之间形成的吸附的curium在矿物表面和溶解的硅酸盐溶液中。一个类似的curium-silicate复合物具有相同的光谱特征，也发现在调查中与α-氧化铝作为吸附剂相后，添加硅的矿物悬浮液，这表明硅络合与表面结合的curium是独立的吸附剂材料。(C)2012爱思唯尔有限公司保留所有权利。
Cm(III) speciation in natural kaolinite (St. Austell, UK) suspensions under alkaline conditions was studied by time-resolved laser fluorescence spectroscopy (TRLFS). The spectroscopic investigations were performed under argon atmosphere (O-2 < 1 ppm) using a constant curium concentration, ionic strength and mineral content of 2 x 10(-7) M, 1 mM NaClO4 and 0.25 g/L, respectively, throughout the study. The impact of kaolinite mineral dissolution on the speciation of the trivalent actinide was investigated in oversaturation experiments where excess amounts of aluminum and/or silicon were added to alkaline kaolinite suspensions. Only silicon addition was found to influence the curium ligand-field under the experimental conditions indicating the formation of a curium-silicate complex in the kaolinite environment. In experiments with 10(-3) M added silicon but no solid phase for curium attachment only the hydrolysis species Cm(OH)(2)(+) could be detected at pH 10. Thus, the formation of colloidal silicate species for the attachment of curium could be excluded and the observed species in alkaline kaolinite environments could be assigned to a ternary kaolinite/curium/silicate complex forming between adsorbed curium at the mineral surface and dissolved silicates in solution. A similar curium-silicate complex with identical spectroscopic features was also found in investigations with alpha-alumina as sorbent phase upon addition of silicon to the mineral suspensions, suggesting that silicon complexation with surface-bound curium is independent of the sorbent material. (C) 2012 Elsevier Ltd. All rights reserved.