Synergistic extraction of REE and TPE from HNO3 solutions with a mixture of CCD and HDBP ZS (1: 6) in a polar diluent

Research paper by D. N. Shishkin, Yu. S. Fedorov

Indexed on: 01 Mar '10Published on: 01 Mar '10Published in: Radiochemistry


Extraction of Ce(III), Am(III), and Eu(III) from HNO3 solutions with acidic zirconium salt of dibutyl hydrogen phosphate (HDBP ZS) at the ratio Zr: HDBP = 1: 6 and with a mixture of HDBP ZS (1: 6) and chlorinated cobalt dicarbollide (CCD) in a polar diluent, mixture of o-chloronitrobenzene and CCl4 (1: 1), was studied. A synergistic effect was observed at a definite ratio of CCD and HDBP in the mixture. The maximal synergistic effect was observed for a mixture of HDBP ZS with CCD and an HDBP to CCD molar ratio of 6:1. The largest magnitude of the synergistic effect was 5 for all the examined elements. The synergistic effect observed in the HDBP ZS (1: 6)-CCD system in extraction of rare-earth and transplutonium elements can be attributed to interaction of Zr, CCD, and HDBP leading to the formation of a complex acid, which is stronger and more hydrophobic than the initial compounds. The stoichiometry of the extraction of Ce and Eu with such acid corresponds to the stoichiometry of the extraction with HDBP ZS and CCD, and in the extraction of Am it is somewhat different. In the extraction ability, this acid considerably surpasses CCD and somewhat surpasses HDBP ZS. The extractability order of metals corresponds to the order of their extractability with HDBP ZS and is opposite to the order of their extractability with CCD. High extraction ability of the complex extractant allows REE and TPE to be recovered directly from the Purex process raffinate.