旨在应用于乏燃料后处理的固相吸附剂研究和制备

固相吸附技术在乏燃料后处理中优势明显，其中高性能、耐酸、抗辐照吸附剂的设计及制备是关键。本项目拟首先选用不同载体材料（介孔硅和聚苯乙烯（Merrifield树脂及超交联微孔共聚物）），共价接枝磷酸酯基团，探讨载体表面及接枝单元极性对磷酯基团构象及配位影响，通过改变接枝参数（如链长、萃取端烷基取代及接枝密度等）和载体孔径，研究磷酯空间位阻及基团间相互作用对核素离子选择性及吸附容量的影响。提出吸附剂设计、制备的基本原则。其次，开发耐辐照多孔共聚物（共轭微孔聚合物（CMP）及共价有机骨架（COF））在该领域的应用。尝试在芴-苯基CMP上修饰多种萃取基团（如TBP、CMPO、TODGA等），研究该载体普适性。充分利用二维COF规整的孔道结构，优化萃取基团在孔道内空间分布、接枝参数，并与孔道形状及尺寸匹配，得到性能优异、稳定性高的吸附剂。制备吸附剂/石墨烯复合过滤膜或气凝胶便于实际使用中操作及回收。

Solid-phase adsorption technique is very attracting for the reprocessing of spent fuel. This project plans to investigate the factors which affect the adsorption behavior of uranium and other radioactive isotopes on organic extractant-grafted adsorbents especially in 2-5 M HNO3 solutions. Representative solid-phase supports (e.g., mesoporous silica and polystyrene (Merrifield resin and hyper-cross-linked polymer)) are employed to identify the influence of surface polarity on the configuration of covalently grafted organic extractants and their coordination with targeted metal ions. As for the polystyrene supports, different grafting parameters (e.g., the polarity of grafting units, grafted density, chain length, and alky substituents in extractant terminals) and pore size are optimized to improve both adsorption capacities and selectivity of the prepared adsorbents. Herein, the steric hindrance in/among grafted functional groups is considered to be responsible. Furthermore, the more application of radiation-resisting porous polymers (e.g., conjugated microporous polymer (CMP) and covalent organic framework (COF)) is explored in this field. Typical extractants (e.g., TBP, CMPO, TODGA, malonamides) are decorated on the fluorine-benzene based CMP to examine the extensive effectiveness of this support. On the basis of the easily tuned 1D pore structure of 2D COF, COF skeletons with chemical stability, weaker polarity, and high crystallinity are firstly screened; the ligand location in the pores could be ascertained, and bearing pore shape and size in mind, the grafting parameters are decided. Eventually, the prepared solid-phase adsorbents with excellent performance could be utilized in the reprocessing of spent fuel, moreover obeying the neutral complex extraction mechanism. Besides, the adsorbents could be incorporated with graphene to fabricate easily handled filtration membranes or macroscopic aerogel adsorbents, which is important in the practical use.