核级锆铪分离树枝状大分子的设计合成及构效关系研究

Zirconium and hafnium co-exist in nature, but they have opposite nuclear characteristics. Thus, they have to be separated prior to their transformation into pure metals. And extractants such as methyl isobutyl ketone (MIBK), N235 and TBP are applied into solvent extraction, but in light of their disadvantages of great treatment capacities, high efficiency and environmental pollutions, industrializations are restricted. The demand for development of high efficient methods of using highly specific ion recognition extractant to separate zirconium from hafnium is needed urgently.On the research of separation zirconium and hafnium by silica gel modified crown ether, as precise molecular structure，high geometries symmetry，a large number of funetional groups，cavities with in the molecular，controllable molecular weight，nano-size molecular shape and highly branched topology of dendrimer，the purpose of this study is to design and synthesis some dendrimers. All of the fundamental knowledge delivered from this study allows us to develop a more efficient, low cost process for separation Zirconium from Hafnium. this subject will focus on the design, synthesis and Zr-Hf separtion of noveldendriners. Main contents are:(1) by means of computational chemistry, building theoretical models, in-depth study of structure-property relationship of dendrimer for new structural optimization and molecular design;(2) synthesis of dendrimers: focus of new structures containing nitrogen and oxygen- matrix, and exploring the green synthesis;(3) Zr-Hf separation performance evaluation of new dendrimers: the investigation of binding ability between Zr-Hf ions and dendrimers in molecular level by UV, fluorescence， EPR， electrochemistry etc. On the evaluation of extraction process dynamics, extraction capacity, viscosity and stripping ability, to find out potential efficient Zr-Hf separation extractants. All of the fundamental knowledge delivered from this study allows us to develop a more efficient, low cost process for separation Zirconium from Hafnium.

锆铪具有相似的化学性质和相反的核性能，锆铪分离是制备核级锆铪材料的关键。传统的锆铪分离工艺存在着严重的污染问题，工业应用受到限制，亟需开发环境友好型锆铪分离新技术。本项目拟采用密度泛函理论对树枝状大分子进行结构优化计算，设计、合成具有特定官能团与锆铪离子匹配的新型萃取剂；探究树枝状大分子的特定官能团的配位作用与锆铪分离的选择性规律；揭示树枝状大分子结构与锆铪萃取性能的构效关系，反馈优化分子设计与合成；通过紫外、荧光等分析手段筛选出对铪具有较高选择性的树枝状大分子，并将其负载到硅胶上，填装成分离柱，实现锆铪的固相分离萃取。该法有利于减少萃取剂的用量与损失，提高萃取剂的循环使用，实现锆铪的高效、绿色分离。研究结果对阐明树枝状大分子与锆铪的作用机理具有重要的意义，并有望为树枝状大分子经济高效分离锆铪提供新途径。

锆铪具有相似的化学性质和相反的核性能，锆铪分离是制备核级锆铪材料的关键。传统锆铪分离工艺存在严重的污染问题，工业应用受到限制，亟需开发环境友好型锆铪分离新技术。本课题通过DFT理论分析，设计出含有N、O、P元素为功能基团的树枝状大分子。通过紫外、荧光分析筛选出对锆铪具有较高选择性的萃取剂，并将其硅胶负载，以期实现锆铪的高效、绿色分离。具体结果如下：.（1）DFT理论计算分析表明，不同的水相环境下，锆铪离子的赋存状态和离子半径不同。.（2）DFT理论计算分析得到G1.0-G4.0 PAMAM型树枝状大分子的四极矩Qii，偶极矩μ，熵S和总能量ET等量子化学参数，用线性回归方法建立了PAMAM-SA大分子与ZrO2+，HfO2+配位稳定常数的结构-性能定量关系( QSPR) 模型，预测所设计的G1.0-G4.0代PAMMA-SA大分子对Zr4+的选择性优于Hf4+，并筛选出理论上与锆铪匹配能力最强的树枝状大分子G2.0-PAMAM-SA。.（3）紫外光谱分析表明， PAMAM-SA型树枝状大分子对锆铪离子具有较好的选择性，且对Zr4+的选择性优于Hf4+。荧光光谱滴定分析表明G1.0-G4.0 PAMAM-SA大分子与Zr4+和Hf4+离子的摩尔结合比分别为1:4, 1:8, 1:10 和 1:16，且G2.0-PAMAM-SA树枝状大分子对Zr4+表现出最好的选择性，与理论计算结果一致。.（4）萃取分离实验表明，G1.0-G4.0 PAMAM-SA大分子萃取性能符合以下规律：G2.0-PAMAM-SA>G1.0-PAMAM-SA>G3.0-PAMAM-SAG4.0-PAMAM-SA。且G2.0-PAMAM-SA大分子对Zr(Ⅳ)和 Hf(Ⅳ)最大萃取率可达98.9%和65.2%，分离系数Zr/Hf最大可达1.52。.（5）所设计的含P硅胶负载PAMAM型大分子SiO2-G1.0-P和SiO2-G2.0-P对锆的吸附量最大值分别为105.87 mg/g和113.51 mg/g，对铪的吸附量最大值分别为18.48 mg/g和20 mg/g。.（6）通过量子化学计算，建立了树枝状大分子结构与萃取特性的内在关联，结果表明萃取剂的HOMO轨道能量越高，电子越活跃，引入给电子基团可以有效提高分子的活性以及与金属离子的结合能力。.此外，还探究了凹凸棒负载树枝状大分子对Hg2+的吸附