多级结构氧化物用于海水中铀的富集与熔盐电解分离研究

Based on the shortage of land uranium resources in China, this proposal is to extract uranium from the sea and then separate by the molten salt electrolytic process. Hierarchical structured oxides with high selectivity and high adsorption capacity are to be synthesized by electrostatic spinning self-assembly, solvent evaporation induced self-assembly, and macromolecular block copolymer template method, which is to propose the research project of uranium extraction and further seperation by molten electrolytic process. Influence of the hierarchical structures of adsorbent, interface coordination characteristics, and morphologies of adsorbents on the uranium adsorption capacity will be investigated in detail, which is to verify the thermodynamic model and dynamic model during the adsorption process. The electronic structure of the uranyl ion and adsorption reaction mechanism during the adsorption process will be studied by the spectroscopy data of the adsorbent before and after adsorption. Thus, uranyl ion and absorbent interface interaction and microscopic mechanism are to be revealed from molecular level. By virtue of the fact that oxides cannot dissolve in the molten salt while uranium (VI) ions can dissolve and have positive electrochemical potential, the electrolysis reaction mechanism of uranium in molten salt is systematically studied, which is to explore the way to effectively separate uranium and adsorbent. This project is to provide the basic data and theoretical guidance for the extraction of uranium from sea, which is of great significance for the sustainable development of nuclear energy.

本项目针对我国陆地铀资源的短缺，开展海水中铀的提取与熔盐电解分离研究。拟通过静电纺丝自组装、溶剂蒸发诱导自组装、大分子嵌段共聚物模板法合成具有高选择性、高吸附容量的多级结构氧化物吸附剂，提出了"铀提取-熔盐电解分离" 一体化的海水提铀研究方案。系统研究吸附剂的多级结构、界面协同特性、形貌对铀吸附性能的影响，验证多级结构铀吸附剂在吸附过程的热力学模型、动力学模型；利用吸附剂对铀吸附前后的光谱学实验数据，采用密度泛函理论计算方法，研究吸附过程铀酰离子电子结构、吸附反应机理，从分子水平上揭示铀酰离子与吸附剂界面的相互作用及微观机理；利用多级结构氧化物不溶于熔盐，而铀酰离子溶于熔盐体系且电极电位比较正的原理，采用熔盐电解法系统研究铀酰离子熔盐电解的反应机理，探索铀酰离子与吸附剂有效分离的途径，为海水中铀的提取与分离研究提供基础性研究数据及理论指导，这对于我国核能的可持续发展具有重要意义。

本项目针对我国陆地铀资源短缺的实际问题，开展海水中铀的提取与分离的基础研究。项目设计合成了5种代表性核壳磁性吸附材料，为铀吸附材料的分离提供了前期研究基础。通过溶剂蒸发诱导自组装、模板法、溶剂热及水热等方法合成6种选择性高、吸附容量较大的多级介孔结构吸附材料和空心球吸附材料，其中介孔氧化镁在已知氧化物中吸附容量最大，最大吸附量为3111 mg/g，在低浓度铀吸附方面应用前景广泛。考虑到工业废料油岩灰资源化的综合利用，以其为原料通过简单的制备工艺获得高效率的类水滑石铀吸附材料。本项研究系统地研究了吸附剂的多级结构、形貌对铀吸附性能的影响，验证了多级结构铀吸附剂在吸附过程的热力学模型和动力学模型；研究了海水中主要离子对于铀吸附的竞争影响，对于吸附反应机理进行了深入的探讨，探索铀离子与吸附剂有效分离的途径，为海水提铀提供基础性研究数据及理论指导，对下一阶段的实海试验积累了实验数据，对于“海水提铀”进一步工程化应用具有重要指导作用。