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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >A revisit of the cation-cation interactions between NpO_2 ~+ and UO_2 ~(2+) in nitric acid medium and their impact on separation processes: Spectrophotometric and solvent extraction studies
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A revisit of the cation-cation interactions between NpO_2 ~+ and UO_2 ~(2+) in nitric acid medium and their impact on separation processes: Spectrophotometric and solvent extraction studies

机译：NpO_2〜+和UO_2〜（2+）在硝酸介质中的阳离子-阳离子相互作用及其对分离过程的影响：分光光度法和溶剂萃取研究

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There are contradicting reports on the thermodynamics of cation-cation interactions (CCIs; inner/outer sphere) involving NpO_2 ~+ and UO_2 ~(2+). This paper revisits CCIs of NpO _2 ~+ (2 × 10~(-4) M) under varying conditions such as reaction time, nitric acid (2 × 10~(-3)-4 M HNO _3)/uranium (up to 1.2 M) concentrations, and temperature (283-343 K) by spectrophotometric measurements. This study reports for the first time the appearance of a signature peak of Np(iv) (～964 nm) in addition to NpO _2 ~+ (980 nm) and the NpO_2 ~+-UO _2 ~(2+) complex (992 nm). For a pure NpO_2 ~+ solution at 4 M HNO_3, there is a gradual increase in Np(iv) peak intensity with increasing temperature and correspondingly the Np(v) peak diminishes. The CCIs are more favored at higher uranium concentrations. However, the intensity of the 992 nm peak decreases steadily with increasing temperature suggesting the exothermic nature of the complexation process. The thermodynamic data and reported structural studies indicate the formation of an inner-sphere complex under the conditions of this study. In addition, the spectral changes also suggest the formation of Np(iv) even in the presence of uranium at elevated temperatures. Solvent extraction studies using 1.1 M TBP and 1.1 M DHOA solutions in n-dodecane show that NpO_2 ~+-UO_2 ~(2+) complexes are extractable leaving NpO_2 ~+ in the aqueous phase.
机译：关于涉及NpO_2〜+和UO_2〜（2+）的阳离子-阳离子相互作用（CCI;内/外球）的热力学的报道相互矛盾。本文回顾了NpO _2〜+（2×10〜（-4）M）在不同条件下的CCIs，例如反应时间，硝酸（2×10〜（-3）-4 M HNO _3）/铀（直至分光光度法测量浓度（1.2 M）和温度（283-343 K）。这项研究首次报道了除NpO _2〜+（980 nm）和NpO_2〜+ -UO _2〜（2+）络合物（992）之外，Np（iv）（〜964 nm）的特征峰的出现。 nm）。对于在4 M HNO_3下的纯NpO_2〜+溶液，随着温度的升高，Np（iv）峰强度会逐渐增加，并且相应地Np（v）峰会减小。在较高的铀浓度下，CCI更受青睐。然而，随着温度的升高，992 nm峰的强度逐渐降低，表明络合过程的放热性质。热力学数据和报道的结构研究表明，在该研究条件下形成了一个内球复合体。此外，光谱变化还表明即使在高温下存在铀的情况下，Np（iv）的形成。在正十二烷中使用1.1 M TBP和1.1 M DHOA溶液进行溶剂萃取研究表明，NpO_2〜+ -UO_2〜（2+）络合物可萃取，而NpO_2〜+留在水相中。

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