Solvent Extraction of Inorganic Ions with Tri-n-octyl Phosphine Oxide

Abstract

The extraction behavior of about sixty inorganic ions was studied in the respective systems of tri-n-octyl phosphine oxide** -HCI and -HNO3 for a contribution to the radiochemical separation techniques.TOPO was dissolved in toluene and used as its 5% (w/v) solutions. The distribution ratios for each elements were determined in the same way as previous works. The acid dependence curves were obtained for the elements ranging from sodium to uranium, and arranged in the order of the periodic table. In general, the Kd values in HCI system are not only higher than those in HNO3 but many curves show maximal Kd values in the acidity range from 2 to 10 M HCI while many curves show minimal values in HNO3 system.The Kd values or the shapes of curves were found to give strong resemblance to corresponding acid system among TBPO*-HCI and TBP**-HCI or -HNO3 systems. However, different behavior to the TBP case was observed in the extraction of yttrium, lanthanum and lanthanide elements in HNO3 system, i. e., they have high Kd values at 1 M acidity. Uranium also showed clearly different results to TBP extraction at 1 M HNO3.It is also found that the extractability with TOPO is higher than that with TBP.