Highly selective extraction of uranium from seawater is currently extremely challenging. Although the amidoxime group (HAO) is the commonly used ligand in seawater uranium extraction, it also has strong binding capacity for vanadium ion. It has been shown that the introduction of phosphate groups into amidoxime-based adsorbents can improve the adsorption performance of materials through a synergistic effect between functional groups. In this work, we have systematically investigated the selective extraction behavior of the phosphate ligand (methylphosphonic acid, HL₁) for uranyl cation and the synergistic effect with amidoxime using density functional theory (DFT). The electron-donor-substituted derivatives of HL₁ (aminomethylphosphonic acid (HL₂) and methyl phosphate (HL₃)) were also considered. Not unexpectedly, the results show that introduction of HL₁ into the amidoxime-based adsorbents improves the extraction and selectivity for uranyl cations. This is mainly due to the fact that HL₁ is more likely to deprotonate, which promotes the dissociation of [UO₂(CO₃)₃]^4–, and the presence of the phosphate groups in the synergistic complexes alters the optimal coordination mode of VO₂⁺. In addition, the HL₂ and HL₃ ligands further improve the uranium extraction performance, especially for HL₃. This work provides guidelines for the rational design of sequestering ligands for uranium extraction from seawater.

中文翻译：

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磷酸盐和酰胺肟对海水中铀回收的协同作用的理论探索


目前，从海水中高度选择性地提取铀极具挑战性。虽然氨基肟基团 （HAO） 是海水铀萃取中常用的配体，但它对钒离子也具有很强的结合能力。研究表明，在氨基肟基吸附剂中引入磷酸基团可以通过官能团之间的协同作用提高材料的吸附性能。在这项工作中，我们使用密度泛函理论 （DFT） 系统研究了磷酸配体 （甲基膦酸，HL₁） 对铀酰阳离子的选择性提取行为以及与酰胺肟的协同作用。还考虑了 HL₁ 的电子供体取代衍生物 （氨基甲基膦酸 （HL₂） 和磷酸甲酯 （HL₃））。不出所料，结果表明，将 HL₁ 引入基于氨基肟的吸附剂中提高了铀酰阳离子的提取和选择性。这主要是由于 HL₁ 更有可能去质子化，这促进了 [UO₂（CO₃）₃]^4–的解离，并且协同复合物中磷酸基团的存在改变了 VO₂⁺ 的最佳配位模式。此外，HL₂ 和 HL₃ 配体进一步提高了铀的提取性能，尤其是 HL₃。这项工作为从海水中提取铀的封存配体的合理设计提供了指导。