新型次锕系元素萃取分离配体的分子设计与实验研究

Recently，selective extraction of minor actinides is one of the most challenging technical problems in spent fuel reprocessing. Study of radioactive systems just by experimental techniques is not only time consuming and expensive, but also needs very strict restrictions and requirements to operations. This project aims to design and synthesize highly efficent N-donor extractants for separating minor actinides from lanthanides with a multiscale stragety combining computational chemistry and experimental techniques. Firstly, the computional chemistry investigations will be peformed to study the coordination and aqueous chemistry of minor actinides/lanthanides with terdentate N-donor ligands such as BTBPs and BTPhens; The basic properties inlcuding structure, spectra, bonding nature, electron transfer,thermodynamics and kinetics of ligands as well as their complexes with actinides will be probed;The diffusion and partition behavior of actnide complexes will be explained; The correlation between structural features of ligands and metal-ligand bonding strength will be eplained.Based on these works, we will diesign and synthesize novel N-donor ligands in experiment, and test their extraction and separation efficiency towards minor actinides from lanthanides. For real application, the performance of ligands in radiation and hydrolytic resistance will also be verified. This work can enhance the application of N-donor ligands in extraction and separation of minor actinides.

当前，选择性萃取长寿命的次锕系元素是乏燃料后处理中最具挑战的技术难题之一。单纯依靠实验手段研究放射性体系不仅耗时长、费用昂贵，对实验操作条件也有着非常严格的限制和要求。本项目拟结合多尺度计算化学方法和实验手段，从分子尺度上设计和合成对次锕系元素具有优良萃取分离能力的新型含N配体萃取剂。拟首先采用计算化学方法研究BTBPs、BTPhens等四齿含N软配体与次锕系元素和镧系元素的配位化学和水溶液化学，考察络合物种的结构，光谱特性、成键性质、电荷转移机制、热力学和动力学行为等，阐释络合物种在水/油界面的分配过程和扩散行为，探寻配体结构和配位强度等与萃取效率的内在关联；在此基础上设计和合成新型含N配体，考察新配体的MAs萃取性能与萃取机理，测试配体的抗水解和抗辐解能力等。通过该工作可获得次锕系元素含N配体的分子设计规律，推动含N配体萃取剂在MAs萃取分离方面的应用。

当前，选择性萃取长寿命的次锕系元素是乏燃料后处理中最具挑战的技术难题之一。单纯依靠实验手段研究放射性体系不仅耗时长、费用昂贵，对实验操作条件也有着非常严格的限制和要求。基于量子化学计算和分子动力学模拟，本项目系统地研究了BTBPs、BTPhens这两类含N萃取配体的镧锕分离机理，获得了大量的萃取热力学数据，探讨了5f/6d价电子行为与萃取选择性之间的可能关联，总结了锕/镧离子半径差异对于次锕系选择性的影响，尤其是解释了络合物中差异与萃取效率之间的构效关系，为未来的配体设计和实验研究提供重要参考。基于理论研究基础，在实验方面开展了次锕系元素萃取配体的设计和合成工作，获得多个高效萃取配体，对其U、Pu、Am萃取选择性、动力学等做了大量的测试与表征工作，结果显示这几种配体均表现出良好的选择性。本项目的研究成果可为未来改进和优化镧锕分离流程提供重要参考。