Microscopic Structures of Tri-n-butyl Phosphate/n-Octane Mixtures by X-ray and Neutron Scattering in a Wide q Range
Microscopic Structures of Tri-n-butyl Phosphate/n-Octane Mixtures by X-ray and Neutron Scattering in a Wide q Range
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通过 X 射线和中子散射在宽 q 范围内观察磷酸三正丁酯/正辛烷混合物的微观结构
DOI：
10.1021/jp210808r
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发表时间：
2012
期刊：
影响因子：
3.3
通讯作者：
and T. Yaita
中科院分区：
文献类型：
--
作者：
R. Motokawa;S. Suzuki;H. Ogawa;M. R. Antonio;and T. Yaita
磷酸三丁酯（TBP）是从废核燃料中萃取分离铀、钚的重要萃取剂。在这种使用TBP的溶剂萃取中，有机相有时分离成两个有机相，即轻有机相和重有机相。第三阶段被称为第三阶段。本工作的目的是阐明第三相形成的机制，在两相液-液溶剂萃取重金属离子。为此，小和广角X射线和中子散射（SWAXS和SWANS）实验进行检查TBP/辛烷混合物的微观结构。这些调查的溶质协会在含TBP的有机相萃取前的重金属离子系统性能提供了见解。例如，在萃取重金属离子之后，在有机相中形成的微观结构可能与此处揭示的初始微观结构相关。SWAXS和SWANS对所有溶液样品的非相干散射强度进行了精确的估算，结果表明：（i）TBP在正辛烷中自缔合，TBP分子间的平均距离为0.9- 1.0nm，TBP分子间的平均距离为0.9- 1.0nm，TBP分子间的平均距离为0.9- 1.0nm;和（iii）在辛烷中TBP组装体之间的吸引相互作用是微小的，因此，由于排除体积效应，它们倾向于均匀分散。
Tri-n-butyl phosphate (TBP) is an important extractant for separating hexavalent uranium and tetravalent plutonium from used nuclear fuel by solvent extraction. In such solvent extractions using TBP, the organic phase occasionally separates into two organic phases, namely, light and heavy organic phases. The latter one in particular is called the third phase. The purpose of this work is to elucidate the mechanism whereby the third phase forms in biphasic liquid–liquid solvent extraction of heavy metal ions. Toward this end, small- and wide-angle X-ray and neutron scattering (SWAXS and SWANS) experiments were conducted to examine the microscopic structures of TBP/octane mixtures. These investigations of solute associations in TBP-containing organic phases before extraction of heavy metal ions provide insights into system performance. After the extraction of heavy metal ions, for example, the microscopic structures formed in the organic phase are likely to be correlated with the initial microscopic structures, which are revealed here. SWAXS and SWANS, with accurate estimations of incoherent scattering intensities for all solution samples, revealed the following: (i) TBP self-associates in octane, and the average distance between two TBP molecules in the TBP assemblies is evaluated as 0.9–1.0 nm; (ii) the shape of the TBP assembly is ellipsoidal; and (iii) the attractive interaction among TBP assemblies in octane is miniscule, and thus, they tend to be dispersed homogeneously due to the excluded volume effect.