Selective extraction of Hf(IV) over Zr(IV) from aqueous H2SO4 solutions by solvent extraction with acidic organophosphorous based extractants

BACKGROUND: The present paper describes the selective extraction of Hf(IV) over Zr(IV) using two acidic extractants (D2EHPA and Cyanex 272) and its mixture with LIX 63 from sulphate medium. To achieve this, extractant and H2SO4 concentrations were varied and results obtained. RESULTS: Selective extraction of Hf(IV) over Zr(IV) was possible using D2EHPA/or Cyanex 272 at 2 mol L-1 and higher H2SO4 solutions. For all investigated experimental conditions, D2EHPA exhibited greater efficiency than Cyanex 272 for the extraction of Hf(IV). Compared with either D2EHPA or Cyanex 272 alone, binary extractant mixtures (D2EHPA+LIX 63, Cyanex 272+LIX 63) did not show much selectivity towards the extraction of Hf(IV) over Zr(IV). Extraction with D2EHPA at 4 mol L-1 H2SO4 solution led to a separation factor around 30 between Hf(IV) and Zr(IV). CONCLUSIONS: Hf(IV) was selectively extracted over Zr(IV) in the investigated systems, with a good separation factor. Results indicated the possibility of separating the metal ions by selective extraction of Hf(IV). The selective extraction of Hf(IV) is important and advantages in separation give the potential for application in nuclear science and technology. (C) 2013 Society of Chemical Industry