Theoretical studies on the complexation of Eu(Ⅲ) and Am(Ⅲ) with HDEHP： structure, bonding nature and stability  

作　　者：juan luo congzhi wang jianhui lan qunyan wu yuliang zhao zhifang chai changming nie weiqun shi 

机构地区：[1]school of chemistry and chemical engineering,university of south china,Hengyang 421001,China [2]laboratory of nuclear energy chemistry and key laboratory for biomedical effects of nanomaterials and nanosafety,institute of high energy physics,chinese academy of sciences,Beijing 100049,China [3]school of radiological and interdisciplinary sciences(rad-x)and collaborative innovation center of radiation medicine of jiangsu higher education institutions,soochow university,Suzhou 215123,China

出　　处：《Science China Chemistry》2016年第3期324-331,共8页中国科学（化学英文版）

基　　金：the National Natural Science Foundation of China (21201166, 11275090);the Major Research Plan of Natural Science Foundation of China (91426302, 91326202);the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA030104);the Natural Science Foundation of Hunan Province (12JJ9006);the Scientific Research Fund of Hunan Provincial Education Department (12A116)

摘　　要：Separation of trivalent lanthanides （Ln（Ⅲ）） and actinides （An（Ⅲ）） is a key issue in the advanced spent nuclear fuel repro- cessing. In the well-known trivalent actinide lanthanide separation by phosphorus reagent extraction from aqueous komplexes （TALSPEAK） process, the organophosphorus ligand HDEHP （di-（2-ethylhexyl） phosphoric acid） has been used as an efficient reagent for the partitioning of Ln（Ⅲ） from An（Ⅲ） with the combination of a holdback reagent in aqueous lactate buffer solu- tion. In this work, the structural and electronic properties of Eu3＋ and Am3＋ complexes with HDEHP in nitric acid solution have been systematically explored by using scalar-relativistic density functional theory （DFT）. It was found that HDEHP can coordinate with M（Ⅲ） （M=Eu, Am） cations in the form of hydrogen-bonded dimers HL2 （L=DEHP）, and the metal ions pre- fer to coordinate with the phosphoryl oxygen atom of the ligand. For all the extraction complexes, the metal-ligand bonds are mainly ionic in nature. Although Eu（Ⅲ） complexes have higher interaction energies, the HL2- dimer shows comparable affini- ty for Eu（Ⅲ） and Am（Ⅲ） according to thermodynamic analysis, nonahydrate. It is expected that this work could provide insightful HDEHP at the molecular level. which may be attributed to the higher stabilities of Eu（Ⅲ） information on the complexation of An（Ⅲ） and Ln（Ⅲ） withSeparation of trivalent lanthanides(Ln(Ⅲ)) and actinides(An(Ⅲ)) is a key issue in the advanced spent nuclear fuel reprocessing. In the well-known trivalent actinide lanthanide separation by phosphorus reagent extraction from aqueous komplexes(TALSPEAK) process, the organophosphorus ligand HDEHP(di-(2-ethylhexyl) phosphoric acid) has been used as an efficient reagent for the partitioning of Ln(Ⅲ) from An(Ⅲ) with the combination of a holdback reagent in aqueous lactate buffer solution. In this work, the structural and electronic properties of Eu^(3+) and Am^(3+) complexes with HDEHP in nitric acid solution have been systematically explored by using scalar-relativistic density functional theory(DFT). It was found that HDEHP can coordinate with M(Ⅲ)(M=Eu, Am) cations in the form of hydrogen-bonded dimers HL_2^-(L=DEHP), and the metal ions prefer to coordinate with the phosphoryl oxygen atom of the ligand. For all the extraction complexes, the metal-ligand bonds are mainly ionic in nature. Although Eu(Ⅲ) complexes have higher interaction energies, the HL_2^- dimer shows comparable affinity for Eu(Ⅲ) and Am(Ⅲ) according to thermodynamic analysis, which may be attributed to the higher stabilities of Eu(Ⅲ) nonahydrate. It is expected that this work could provide insightful information on the complexation of An(Ⅲ) and Ln(Ⅲ) with HDEHP at the molecular level.

关 键 词：density functional theory di-(2-ethylhexyl) phosphoric acid actinide LANTHANIDE solvent extraction 

分 类 号：O641.1[理学—物理化学]