Extraction of pertechnetate anion as a ligand in metal complexes with tributylphosphate

The extraction of the pertechnetate anion has been investigated in the systems tributylphosphate (TBP)—solvent (carbon tetrachloride, n-heptane, chloroform)—metal salt (uranyl nitrate and chloride, thorium nitrate)—ammonium salt. In the absence of a metal, the solvates HTeO₄. iTBP (i=4) are extracted, while in the presence of uranium and thorium, the distribution of technetium corresponds to the formation of the mixed complexes: UO₂(NO₃)(TeO₄)·2TBP, UO₂Cl(TcO₄)·2TBP and Th(NO₃)₃ (TcO₁)·2TBP. The effective constants of the reactions H⁺+TcO ₄ ⁻ +i(TBP)_org←(HTcO₁·iTBP)_org, and (ML_n·2TBP)_org+TcO ₄ ⁻ ←(ML_n−1TcO₄·2TBP)_org+L were established in the above systems. The extraction of pertechnetate ion is more effective when it is coordinated to a cation solvated by TBP than the extraction in the form of pertechnetate acid solvated by TBP.