Jiangxi Key Laboratory for Mass Spectrometry and Instrumentation, East China University of Technology, Nanchang, Jiangxi 330013, China.
Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
Inorg Chem. 2023 Mar 20;62(11):4581-4589. doi: 10.1021/acs.inorgchem.2c04476. Epub 2023 Mar 9.
The separation of lanthanides and actinides has attracted great attention in spent nuclear fuel reprocessing up to date. In addition, liquid-liquid extraction is a feasible and useful way to separate An(III) from Ln(III) based on their relative solubilities in two different immiscible liquids. The hydrophilic bipyridine- and phenanthroline-based nitrogen-chelating ligands show excellent performance in separation of Am(III) and Eu(III) as reported previously. To profoundly explore the separation mechanism, herein, we first of all designed four hydrophilic sulfonated and phosphorylated ligands L, L, L, and L based on the bipyridine and phenanthroline backbones. In addition, we studied the structures of these ligands and their neutral complexes [ML(NO)] (M = Am, Eu) as well as the thermodynamic properties of complexing reactions through the scalar relativistic density functional theory. According to the changes of the Gibbs free energy for the back-extraction reactions, the phenanthroline-based ligands L and L have stronger complexing capacity for both Am(III) and Eu(III) ions while the phosphorylated ligand L with the bipyridine framework has the highest Am(III)/Eu(III) selectivity. In addition, the charge decomposition analysis revealed a higher degree of charge transfer from the ligand to Am(III), suggesting stronger donor-acceptor interactions in the Am(III) complexes. This study can provide theoretical insights into the separation of actinide(III)/lanthanide(III) using hydrophilic sulfonated and phosphorylated N-donor ligands.
目前，镧系元素和锕系元素的分离在乏核燃料后处理中受到了极大的关注。此外，基于它们在两种不混溶的液体中的相对溶解度，液-液萃取是一种可行且有用的方法，可将 An(III)从 Ln(III)中分离出来。以前的报道表明，亲水的双吡啶和菲咯啉基氮螯合配体在分离 Am(III)和 Eu(III)方面表现出优异的性能。为了深入探索分离机制，我们首先设计了基于双吡啶和菲咯啉骨架的四种亲水磺化和膦酸化配体 L、L、L 和 L。此外，我们通过标量相对论密度泛函理论研究了这些配体及其中性配合物[ML(NO)]（M = Am，Eu）的结构以及配合反应的热力学性质。根据反萃取反应的吉布斯自由能变化，基于菲咯啉的配体 L 和 L 对 Am(III)和 Eu(III)离子都具有更强的络合能力，而具有双吡啶骨架的膦酸化配体 L 具有最高的 Am(III)/Eu(III)选择性。此外，电荷分解分析表明，配体向 Am(III)转移的电荷程度更高，表明在 Am(III)配合物中存在更强的供体-受体相互作用。这项研究可以为使用亲水磺化和膦酸化 N-供体配体分离锕系(III)/镧系(III)提供理论见解。
