功能化共价有机框架材料对海水中铀酰的选择性富集分离

With the development of nuclear power in China, the demand for uranium resources is increasing over time. However, the uranium deposits in China are complex and low grade, far from meeting the needs for the fast development of nuclear power. Facing the reality of relative scarcity of uranium resources in China and the huge demand gap, this project intends to design and synthesize various functional covalent organic frameworks (COFs) with different pore sizes through grafting oxime, amidoxime, salicylaldoxime and 8-hydroxyquinoline in the channel, which have high affinity and selectivity to uranyl group. These functional COFs will be used to extraction of uranium from seawater. The contents of the research mainly include: 1) Synthesis, characterization and simulation of the functionalized COFs; 2) extraction uranium performance from seawater of COFs, including adsorption capacity, selectivity, kinetics and reuse properties; 3) revelation of adsorption mechanism by EXAFS and XPS, combining with the crystal structures and theoretical calculation of the complexes. This project will lay the experimental foundation for the application of COFs in extracting uranium from seawater. COFs are expected to make a breakthrough in the adsorption capacity and adsorption kinetics for their regular, open, adjustable pore structures. In addition, this project will provide theoretical basis for designing better performance and cheaper adsorption materials.

随着我国核电的不断发展，对铀的需求日益增大。我国陆地铀矿组成复杂且品位偏低，远不能满足核电发展需要。针对我国陆地铀资源相对匮乏和存在巨大需求缺口的现状，本项目拟设计合成孔径不同的共价有机框架（COFs）材料，通过共价接枝肟基、偕胺肟基、水杨醛肟基及8-羟基喹啉等对铀酰具有高亲和力和选择性的基团，制备出一系列功能化的COFs材料并用于海水提铀。研究内容包括：1）COFs材料的合成、结构表征及模拟；2）COFs材料的海水提铀性能，重点考察吸附容量、吸附选择性、动力学及重复利用性质；3）通过先进光谱探测技术（EXAFS和XPS），结合配合物单晶结构和理论计算模拟，深入阐述吸附机理。本项目将为COFs材料在海水提铀方面的应用奠定实验基础；COFs具有规则、开放、可调的孔道结构，有望提升其对铀酰的吸附动力学和吸附容量，同时为进一步设计开发性能更优、成本更低的吸附材料提供理论依据。

发展选择性吸附铀酰等放射性离子的多孔框架材料对于核能的可持续发展具有重要意义。本项目通过后修饰合成法，在共价有机框架材料孔壁接枝偕胺肟基团，合成了对共价纳米片材料CON-AO，并系统研究了其对铀酰的吸附动力学、吸附容量、吸附选择性等多个关键吸附数据。结果表明CON-AO对铀酰的吸附容量为23.52 mg/g。在Mg(Ⅱ)、Ca(Ⅱ)、Co(Ⅱ)、Mn(Ⅱ)、Ni(Ⅱ)和Zn(Ⅱ)等竞争性金属离子存在条件下，CON-AO对铀酰的去除率高达94%。同时，本项目还设计开发了一系列对锝、碘、锶等放射性核素具有良好吸附能力的多孔材料，系统研究了材料对目标核素的吸附性能。通过本项目的实施，获得了对铀等核素具有高效分离能力的多孔吸附剂，结合光谱数据和理论计算，深入揭示了放射性离子与材料骨架相互作用的机理，为高性能吸附材料的设计开发提供了积极的指导意义。