EXTRACTION OF ACTINIDES AND LANTHANIDES BY ALKYLPHENOL SULFIDES

The extraction chemistry of Am and rare earths by S-containing alkylphenol derivatives in the presence of various complexants (K2CO3, K2C2O4, NaC2H3O2) is studied by distribution measurements using C-13 NMR spectroscopy. In these systems, the elements are extracted well by p-tert-butylphenol disulfide (BPDS) and its oligomeric derivative octophor 10S at high pH values, i.e., under conditions where various hydroxo species exist in the aqueous phase. In all probability, the extraction occurs by stripping OH groups from the hydroxo ions and protons from the hydroxyl groups of the reagents. The changes in the C-13 MMR parameters of BPDS resulting from complexation with rare earths are consistent with the substitution of hydroxyl protons by metals to form a M-O bond and additional coordination to the S donor. The experimental data suggest that alkylphenol sulfides extract trivalent actinides and lanthanides from complexing solutions at high pH values as stable chelates.