仲碳伯胺-三辛基氧膦（N1923-TOPO）体系从锆铪料液中选择性协同萃取铪的机理研究

锆铪萃取分离是生产核级锆铪和发展核能产业的技术关键。传统MIBK溶剂萃取分离工艺萃取剂水溶性大、环境污染严重；而多数替代萃取体系则优先萃锆，分离效率低。因此，开发新型绿色高效的锆铪萃取分离体系迫在眉睫。前期研究发现，N1923-TOPO体系可从高浓度锆铪料液中优先萃取含量较少的铪，铪萃取率达82%，铪锆分离系数达13.5，优于MIBK法。本项目拟探索N1923-TOPO体系萃取剂配比、水相酸度、锆铪浓度、稀释剂类型等因素的影响规律，揭示其协萃效应，优化选萃方法；采用斜率法和饱和容量法研究协萃机理，依据软硬酸碱理论和电中性原理探明萃合物的组成和结构特征，阐释复杂溶剂萃取体系中萃合物配位机制与萃取选择性之间的关系；采用恒界面池法探明该体系对铪的协萃动力学规律，强化铪的萃取传质过程，从而丰富锆铪溶剂萃取分离配位化学理论，拓展协萃体系设计思路，为开发新型绿色高效的核级锆铪分离关键技术提供理论指导。

Extraction and separation of zirconium (Zr) and hafnium (Hf) is the key to preparing nuclear-grade Zr and nuclear-grade Hf, both of which directly affects the development of the nuclear industry. A lot of drawbacks, such as high solubility of the extractant and serious environmental pollution, have already been exposed by the traditional MIBK extraction system. However, most of the alternative extraction system selectively extracts Zr either than Hf which is the minor element in the raw material. The efficiency of these alternative extraction systems has been limited. Therefore, new green and efficient solvent extraction system is urgently needed to separate Hf from Zr. Our previous research found that N1923-TOPO synergistic extraction system could selectively extract Hf over Zr. The extraction rate of Hf could reach 82%, and separation coefficient between Hf and Zr could reach 13.5, both of which were better than that of MIBK system. So it is important to reveal the synergistic extraction effect, and optimize the selective extraction technology for N1923-TOPO system by investigating the influence of different key factors, such as the ratio of extractants, acidity, concentration of metal ions, diluent type and so on. It is important to clarify the mechanism on extraction Hf over Zr by N1923-TOPO system using the slope method and saturation volumetric method, to identify the composition and structure characteristic of the extraction complex according to HSAB theory and electro-neutrality principle, and to illuminate the relationship between the coordination mode and the extraction selectivity for complicated extraction system. And it is also very important to enhance the mass transfer process for extraction and separation Hf over Zr by revealing the extraction kinetics using the Lewis cell. This work would be helpful to enrich the coordination chemistry theory for solvent extraction Hf from Zr, extend the thought for designing new synergistic extraction system, and provide guidance for developing a novel separation technology to prepare nuclear-grade Zr and Hf.