Radiolytic degradation in lanthanide/actinide separation ligands-NOPOPO: Radical kinetics and efficiencies determinations

Katy L. Swancutt, Stephen P. Mezyk, Richard D. Tillotson, Sylvie Pailloux, Manab Chakravarty, Robert T. Paine, Leigh R. Martin

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Trivalent lanthanide/actinide separations from used nuclear fuel occurs in the presence radiation fields that degrades the extraction ligands and solvents. Here we have investigated the stability of a new ligand for lanthanide/actinide separation; 2,6-bis[(di(2-ethylhexyl)phosphino)methyl] pyridine N,P,P-trioxide, TEH(NOPOPO). The impact of γ-radiolysis on the distribution ratios for actinide (Am) and Lanthanide (Eu) extraction both in the presence and absence of an acidic aqueous phase by TEH(NOPOPO) was determined. Corresponding reaction rate constants for the two major radicals, hydroxyl and nitrate, were determined for TEH(NOPOPO) in the aqueous phase, with room temperature values of (3.49 ± 0.10) × 109 and (1.95 ± 0.15) × 108M-1s-1, respectively. The activation energy for this reaction was found to be 30.2 ± 4.1 kJ mol-1. Rate constants for two analogues (2-methylphosphonic acid pyridine N,P-dioxide and 2,6-bis(methylphosphonic acid) pyridine N,P,P-trioxide) were also determined to assist in determining the major reaction pathways.

Original languageEnglish (US)
Pages (from-to)637-654
Number of pages18
JournalSolvent Extraction and Ion Exchange
Volume29
Issue number4
DOIs
StatePublished - Jul 1 2011

Keywords

  • Actinide lanthanide separation
  • Radiolysis
  • Solvent extraction

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