Study on the Solvent Extraction with Radio‐Tracers. II. Solvent Extraction of Polonium‐210 from Irradiated Bismuth with tri‐n‐butyl Phosphate

Abstract Extraction study on polonium from large amounts of irradiated bismuth was made with diluted TBP solution. Polonium used in this work was Po‐210, which was prepared by the irradiation of bismuth according to the following nuclear reaction, . From this study the following extraction conditions were obtained. Extraction from 7 N HCl was found to be most suitable. Degree of the dilution of TBP with diluent was studied and TBP concentration at about 10% was found to be most effective. With various kinds of the solvent as diluent, the following order of the extraction was found: o‐xylene>carbon tetrachloride>benzene>amy1 alcohol>chloroform. Extraction of polonium with 10% TBP in o‐xylene from 7 N HCl solution, more than 85% was found to be extracted with a single extraction. Under these conditions only a negligible amount of bismuth was extracted. Thus, the separation of these two elements was attained with this method. From the study on the distribution coefficients dependence on the variation of the concentration of TBP or acidities, the species extracted by the organic layer was considered to be PoCl4·2TBP when TBP concentration was less than 50% TBP, but PoCl4·TBP when larger than 50% TBP.