含磷类萃取剂/羧基功能离子液体相转移萃取体系分离UO22+的研究

The reprocessing of spent nuclear fuel is the key process of advanced nuclear fuel cycle. In recent years, room temperature ionic liquids have been considered as alternative medias to replace traditional organic diluents in the reprocessing of spent nuclear fuel. The solubility of carboxyl-functionalized task-specific ionic liquids (TSILs) in water can be adjusted by incorporating functional groups into ionic liquids. Long equilibrium time for extraction can be greatly cut down, and a fast contact between extractant and metal ions can be achieved through formation of a homogeneous phase compared with traditional extraction. The feasibility of fast homogeneous extraction of UO22+ by a new homogeneous extraction system with phosphine oxide ligand/TSILs was assessed in this project. The selectivity, extraction efficiency, extraction mechanism, and radiation stability of phosphine oxide ligand/TSILs system were investigated by experimental study with DFT validation. This study will be significant in its further evaluation and practical application of phosphine oxide ligand/TSILs system.

乏燃料的后处理是先进核燃料循环中的关键环节，近年来研究表明离子液体有望取代传统有机溶剂应用于乏燃料后处理中，具有配位能力的羧基功能性离子液体在相转变萃取中可实现金属离子的快速分离。本研究提出将羧基功能离子液体体系的相转变萃取分离特性与含磷类萃取剂的较高耐酸性结合起来，探索含磷类萃取剂/羧基功能离子液体体系用于UO22+分离的可能性。通过实验模拟与理论计算的结合，研究含磷类萃取剂/羧基功能离子液体体系的萃取性能、萃取机理、辐射稳定性。这对含磷类萃取剂/羧基功能离子液体体系的进一步研究与应用具有重要意义。

本项目基于理论计算的研究，结合一系列的实验研究，解析了含磷类萃取剂/羧基咪唑功能离子液体体系相转变萃取UO22+的萃取机理，并且对含磷类萃取剂、羧基咪唑功能离子液体、含磷类萃取剂/羧基咪唑功能离子液体等体系的辐射效应进行了评估，认识了含磷类萃取剂、羧基咪唑功能离子液体、含磷类萃取剂/羧基咪唑功能离子液体等体系的辐射降解行为，同时利用高分辨电喷雾质谱成功获取了其主要辐射降解产物的化学结构，为萃取体系的辐射效应评估提供了重要支撑。研究中发现含磷类萃取剂/羧基咪唑功能离子液体体系对高浓度UO22+具有很好的分离性能，这为含磷类萃取剂/羧基咪唑功能离子液体体系的应用提供了重要的支撑。