Chromatographic Study of Rutherfordium (Element 104) in the System HCl/Tributylphosphate (TBP)

Abstract

Liquid-liquid extractions of ⁹⁵Zr and ¹⁷⁵Hf from various concentrations of HCl were conducted using tributylphosphate (TBP) in toluene (benzene), and undiluted TBP. Quantitative extraction of both Zr and Hf into TBP in toluene (benzene) was observed from ≥ 8 M HCl and into undiluted TBP from ≥ 10 M HCl. Extraction from 8 M HCl into undiluted TBP was 80% for Zr and 20% for Hf. Based on these results, a chromatographic separation of Hf from Zr with the Automated Rapid Chemistry Apparatus ARCA II was performed on 1.6×8 mm columns containing undiluted TBP on an inert support. This separation was also studied on-line with short-lived ¹⁶⁹Hf produced in the Gd(¹⁸O, xn) reaction and with 78-s ²⁶¹Rf produced in the ²⁴⁸Cm(¹⁸O, 5n) reaction at the Philips Cyclotron of the Paul Scherrer Institute. From the distribution of <em>α</em>-decays of ²⁶¹Rf between the Hf- and Zr-fraction, the <em>K_d</em>-value for Rf in 8 M HCl was determined, and the following extraction trend was established: Zr &gt; Rf &gt; Hf. This is at variance with earlier results where Rf seemingly did not extract as well as Hf which was tentatively attributed to increased hydrolysis of Rf.