Third Phase Formation in the Extraction of Zirconium(IV) by TRPO in Kerosene

Abstract

The third phase formation in the extraction of zirconium(IV) from nitric acid media by TRPO(trialkyl phosphine oxide)/kerosene was studied. The limiting organic concentrations (LOC) of Zr(IV) under various experimental conditions were determined. Low temperature and high nitric acid concentrations (> 3 M) were found to facilitate the third phase formation, while increasing the concentration of TRPO or adding phase modifier (TBP) into the organic phase resulted in increased LOC of Zr(IV). When the third phase appeared, the conductivity in the organic phase changed sharply, indicating the change of aggregating behavior in the organic phase. FT-IR spectra were used to illustrate the interaction of TRPO with HNO₃ or Zr(IV), and the composition of the two organic phases indicated by FT-IR spectra was consistent with a diluent-enriched light phase and a zirconium/TRPO-concentrated heavy phase.

Keywords:

• extraction
• third phase formation
• trialkyl phosphine oxide (TRPO)
• zirconium

ACKNOWLEDGEMENTS

This work was supported by National 863 Program of China for its Nuclear Fuel Cycling and Nuclear Safety Technology Project under the Contract 2009AA050703. The authors are grateful to the anonymous reviewers for their comments that help to improve the manuscript.

Notes

^a [H⁺] in the equilibrated aqueous phase was maintained at 1.00 ± 0.05 M. [Zr(IV)] in the organic phase before phase splitting was 3.3 g/L.