A Study of the Interaction of Neptunium(V) with Polyacrylic Acid by Solvent Extraction

T. Kubota, O. Tochiyama, H. Yoshino, K. Tanaka, Y. Niibori

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12 Citations (Scopus)


The interaction of polyacrylic acid ([-CH2CH(COOH)-]n) with Np(V) has been investigated by a solvent extraction method using 239Np (∼10-12M) with TTA and 1,10-phenanthroline in isoamyl alcohol. By defining the apparent formation constant as βapp = [ML]/([M][R]), where [M] and [ML] denote the concentrations of free and bound NpO2+, and [R] the concentration of dissociated carboxyl group, the values of log βapp have been obtained for polyacrylic acid (MW = 2000, 90000 and 450000) at several pH (5-8) and ionic strength (0.1 and 1.0 M of NaClO4 and NaCl). The obtained values ranged from 1.7 to 3.0 depending on the condition; that is, log βapp increased with the degree of dissociation of polyacrylic acid and decreased with ionic strength. These changes were considered to be caused by multidentate coordination of carboxylate groups to NpO2+ ion and by electrostatic attraction between cations and negatively charged polyacrylale ion.

Original languageEnglish
Pages (from-to)15-20
Number of pages6
JournalRadiochimica Acta
Issue number1
Publication statusPublished - 1998


  • Complex formation
  • Humic acid
  • Np(V)
  • Polyacrylic acid
  • Solvent extraction


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