EXTRACTION CHROMATOGRAPHIC BEHAVIORS OF ZIRCONIUM AND HAFNIUM USING SULFOXIDES AS STATIONARY PHASES

The extraction chromatographic behaviors of zirconium(IV) and hafnium(IV) were investigated using dibenzyl sulfoxide (DBSO) and petroleum sulfoxide (PSO) as stationary phases in the media of hydrochloric acid and hydrochloric acid-ammonium thiocyanate by the batch method. In both systems, Zr(IV) and Hf(IV) showed almost the same behavior at higher HCl concentration due to the formation of halo metal acids, H2ZrCl6 and H2HfCl6. In the PSO-HCl-NH4SCN system, the distribution ratios of Zr(IV) and Hf(IV) gave greater values, owing to the formation of ZrO(SCN)(2) and HfO(SCN)(2) at a lower HCl concentration and a decrease along with an increase in the HCl concentration; such phenomena were not observed in the DBSO-HCl-NH4SCN system. The IR spectra of the extracted complexes gave evidence of oxygen in an SQ group coordinating Zr(IV) or Hf(IV) to form extractable species. Finally, a quantitative separation of Zr(IV) and Hf(IV) was achieved using a PSO-extraction chromatographic column (phi 6x220 mm) at 250 degrees C.