Distribution Behavior of U(VI), Pu(IV), Am(III), and Zr(IV) with N,N-Dihexyl Octanamide under Uranium-Loading Conditions
Distribution Behavior of U(VI), Pu(IV), Am(III), and Zr(IV) with N,N-Dihexyl Octanamide under Uranium-Loading Conditions
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铀负载条件下 U(VI)、Pu(IV)、Am(III) 和 Zr(IV) 与 N,N-二己基辛酰胺的分布行为
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发表时间：
2001
期刊：
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通讯作者：
A. Ramanujam
中科院分区：
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作者：
V. Manchanda;P. Β. Ruikar;S. Sriram;M. S. Nagar;P. Pathak;K. Gupta;R. Singh;R. Chitnis;P. S. Dhami;A. Ramanujam
摘要尽管以磷酸三正丁酯(TBP)为基础的Purex工艺在过去的45年里一直是核燃料后处理行业的主力，但与TBP使用相关的一些缺点引起了分离科学家和技术人员的担忧。这些缺点可能构成严重的挑战，特别是在以下过程中：(A)短期冷却的热堆燃料，(B)钚含量较高且燃耗明显较高的快堆燃料，以及(C)处理各种废物以处置到环境中。N，N-二烷基脂肪酰胺作为乏核燃料后处理的替代潜在萃取剂受到了特别关注，因为(A)其降解产物，即羧酸/胺的无毒性质，以及(B)焚烧使用过的溶剂的可能性，从而减少了二次废物的体积。这些酰胺的物理和化学性质受到烷基性质的强烈影响。在众多的萃取剂中，N，N-二己基辛酰胺(DHOA)被认为是一种很有前途的萃取剂。在使用DHOA的工艺条件下进行了实验室批处理研究和混合澄清器研究，并与TBP进行了比较。无论是在痕量浓度还是在铀负载条件下，DHOA都比TBP更有效地提取Pu(IV)。此外，还研究了不同硝酸浓度(1~6M)对Am(III)和Zr(IV)的萃取行为。在不同温度下研究了大浓度铀(9.9~157.7 g/L)的萃取行为，发现DU随铀负载量的增加而减小，随温度的升高(25~45℃)而减小，两相反应本质上是放热反应。混合澄清器对U(VI)的研究表明，在萃取循环中，DHOA与TBP相似，但在反萃循环中优于TBP。
Abstract While the tri-n-butyl phosphate (TBP)-based PUREX process has been the workhorse of the nuclear fuel reprocessing industry for the last four and a half decades, a few drawbacks associated with the use of TBP have caused concern to the separation scientists and technologists. These shortcomings may pose a serious challenge particularly during the reprocessing of (a) short cooled thermal reactor fuels, (b) fast reactor fuels with the larger Pu content and significantly higher burn up, and (c) while treating various waste streams for their disposal to the environment. The N,N-dialkyl aliphatic amides have received particular attention as alternate potential extractants for the reprocessing of spent nuclear fuels in view of (a) the innocuous nature of their degradation products, namely, carboxylic acids/amines and (b) the possibility to incinerate the used solvent leading to reduced volume of secondary waste. The physical and chemical properties of these amides are influenced strongly by the nature of alkyl groups. The extractant N,N-dihexyl octanamide (DHOA) was found to be a promising candidate among a large number of extractants studied. Laboratory batch studies as well as mixer settler studies were performed under process conditions with DHOA and compared with those of TBP. DHOA was found to extract Pu(IV) more efficiently than TBP, both at trace-level concentration as well as under uranium loading conditions. In addition, the extraction behavior of Am(III) and Zr(IV) was studied at varying nitric acid concentrations (1 to 6 M). Extraction behavior of uranium at macroconcentrations (9.9 to 157.7 g/l) was carried out at different temperatures, and it was observed that DU decreased with the increase in U loading as well as with the increase of temperature (in the range 25 to 45°C) and that the two-phase reaction was exothermic in nature. Mixer settler studies on U(VI) revealed that DHOA is similar to TBP during the extraction cycle but better than TBP during the stripping cycle.