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

Juan Luo, Congzhi Wang, Jianhui Lan, Qunyan Wu, Yuliang Zhao, Zhifang Chai, Changming Nie, Weiqun Shi

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

Separation 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 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 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 HL2- 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.

Original languageEnglish (US)
Pages (from-to)324-331
Number of pages8
JournalScience China Chemistry
Volume59
Issue number3
DOIs
StatePublished - Mar 1 2016

Keywords

  • actinide
  • density functional theory
  • di-(2-ethylhexyl) phosphoric acid
  • lanthanide
  • solvent extraction

ASJC Scopus subject areas

  • Chemistry(all)

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