Extraction of tetra- And hexavalent actinide ions from nitric acid solutions using some diglycolamide functionalized calix[4]arenes

Rajesh B. Gujar, Parveen K. Verma, Prasanta K. Mohapatra*, Mudassir Iqbal, Jurriaan Huskens, Willem Verboom

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

5 Citations (Scopus)

Abstract

Neptunium is one of the most important minor actinide elements with some of its isotopes having very long half-lives, therefore necessitating its separation from acidic radioactive wastes. Solvent extraction of Np4+ and NpO22+ was studied using three multiple diglycolamide (DGA) extractants with n-propyl, n-octyl and 3-pentyl substituents termed as LI, LII and LIII, respectively, in a mixed diluent of 5% isodecanol and 95% n-dodecane. For comparison purpose, the extraction of Pu4+ and UO22+ was carried out under identical conditions. The extraction efficiency of the ligands for the tetravalent ions followed the trend: LII > LI > LIII, which changed to LIII > LII > LI for the hexavalent ions. While the extraction of the tetravalent ions was reasonably good (ca. 90-98%) with an extremely low (5.0 × 10−5 M) ligand concentration, poor extraction (ca. 5-16%) of the hexavalent ions was seen even with a 20 times higher concentration of the ligand. In general, Pu4+ was better extracted than Np4+, while NpO22+ was marginally better extracted then UO22+. A 'solvation' type extraction mechanism was proposed based on the extraction profiles obtained as a function of the concentrations of the feed nitric acid, extractant as well as nitrate ion. The extracted species were found out to be M(NO3)4·mL and MO2(NO3)2·nL (M = Np or Pu, 1 < m < 2, n ≃ 1).

Original languageEnglish
Pages (from-to)167-176
Number of pages10
JournalRadiochimica acta
Volume109
Issue number3
DOIs
Publication statusPublished - 1 Mar 2021

Keywords

  • Diglycolamide calix[4]arenes
  • Extraction
  • Neptunium
  • Plutonium
  • Separation

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