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乏燃料后处理中的三价锕系和镧系元素分离是“分离-嬗变”过程的主要环节,对于建立先进核燃料循环具有重要意义。然而,三价锕系和镧系元素结构与性质非常相似,实现二者的分离一直都是分离科学研究领域的难题。溶剂萃取法是三价锕系和镧系元素分离的基本方法之一,而运用含硫、氮等软配位原子的萃取剂则是实现分离的关键。在众多的萃取剂中,含氮杂环化合物因其优良的萃取分离能力,同时符合CHON原则而利于实现废物最小化,近年来引起了广泛的研究兴趣。本文综述了国内外研究报道的典型含氮杂环类三价锕系和镧系元素分离萃取剂,包括三联吡啶、TPTZ、BTP、BTBP以及以TPEN为代表的氮杂环取代胺类萃取剂,对其分离能力、稳定性等性能进行了比较,对萃取机理以及影响其萃取能力的因素等亦进行了说明,并对萃取剂的后续设计、改进提出了参考性建议。
The separation of trivalent actinides and lanthanides from spent fuel reprocessing is a major part of the process of “separation-transmutation”, which is of great significance for establishing an advanced nuclear fuel cycle. However, the structure and properties of trivalent actinides and lanthanides are very similar, and to achieve the separation between them has always been a problem in the field of separation of scientific research. Solvent extraction is one of the basic methods for the separation of actinides and lanthanides. The use of extractants containing sulfur, nitrogen and other soft coordination atoms is the key to separation. Among the many extractants, nitrogen-containing heterocyclic compounds have attracted a great deal of research interest in recent years due to their excellent extraction and separation ability and in line with the principle of CHON. This review summarizes the typical nitrogen-containing heterocyclic trivalent actinide and lanthanide extractants reported in China and abroad, including terpyridine, TPTZ, BTP, BTBP and azole-substituted amine extractants represented by TPEN. The separation performance, stability and other properties were compared. The extraction mechanism and the factors influencing its extraction ability were also described, and some suggestions for the subsequent design and improvement of extractant were also proposed.