Although solid-phase extraction is a useful approach for metal ion separation from aqueous solutions, existing sorbents suffer from low extraction efficiencies and/or instability when in contact with strong acidic media. We report here the first study on rational design and fabrication of phosphonate-decorated covalent organic frameworks, COF-IHEP1 and COF-IHEP2, for efficient and selective extraction of of uranium (VI) [U(VI)] and plutonium(IV) [Pu(IV)] from highly acidic solutions. We found that the negatively charged frameworks with excellent stability under harsh conditions and strong chelating ability from incorporated phosphonate moieties make the COFs superb U(VI) and Pu(IV) sorbents. In 1 M HNO 3 solution, COF-IHEP1 achieved recorded U(VI) uptake of 112 mg·g ?1, with extremely high selectivity toward Pu(IV) even in the presence of large excess of competing metal cations. Our mechanistic study confirms a sandwich-type microstructure of hydrated U(VI) and Pu(IV) cations bound by the oxygen sites of phosphonate groups. These newly fabricated tailored hybrid porous materials could afford new opportunities to achieve highly efficient actinide extraction from acidic nuclear fuel effluents.

中文翻译：

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膦酸酯修饰的共价有机框架用于Act系元素的萃取：在高酸性条件下的突破

尽管固相萃取是从水溶液中分离金属离子的有用方法，但是现有的吸附剂在与强酸性介质接触时，萃取效率低和/或不稳定。我们在此报告有关有效设计和选择性提取铀（VI）[U（VI）]和p（IV）[]的膦酸酯修饰的共价有机骨架COF-IHEP1和COF-IHEP2的合理设计和制造的第一项研究。 Pu（IV）]来自高酸性溶液。我们发现带负电荷的骨架在苛刻的条件下具有出色的稳定性，并结合了膦酸酯基团具有很强的螯合能力，使COF成为极好的U（VI）和Pu（IV）吸附剂。在1 M HNO 3溶液中，COF-IHEP1记录的U（VI）吸收为112 mg·g？1，即使存在大量过量的竞争性金属阳离子，对Pu（IV）的选择性也极高。我们的机理研究证实了水合的U（VI）和Pu（IV）阳离子被膦酸酯基团的氧位所束缚的三明治型微结构。这些新近定制的混合多孔材料可以为从酸性核燃料废水中高效提取act系元素提供新的机会。