AMALGAMATION BEHAVIOR OF HEAVY ELEMENTS .4. TRACER CHEMISTRY OF DIVALENT MENDELEVIUM

In this paper it is shown that the extraction of medelevium into sodium amalgam from sodium acetate solutions results in about a ten fold enrichment relative to the lighter actinides (Pu, Am, Cm, Bk). Separation of Md from the heavier actinides may be accomplished by either of two methods: (1) an amalgam containing Md, Fm, Es, and Cf can be decomposed in cold concentrated HCl and then the Md may be coprecipitated with EuCl2 with one order of magnitude enrichment from Fm; (2) Md can be separated by electrolysis in acetate or citrate-acetate solution on an electrode of mercury amalgamated with sodium. In the lanthanide series method (2) is used to separate Eu or Sm from the other rare earths. The sequence of electrodeposition of actinides in acetate-citrate solution is Md > Fm > Es > Cf. These separation methods probably depend on the formation of stable Md2+. The potential of the Md3+ + e → Md2+ couple was estimated by a series of reductions, using YbCl2, Zn, EuCl2, CrCl2, VCl2, and TiCl3, all in 2 M HCl. All except TiCl3 appear to reduce Md3+ to Md2+, which can then be coprecipitated with EuSO4 or BaSO4; Md is thereby enriched 10-30 X in the precipitate, relative to the daughter isotope 256Fm in solution. © 1969.