The Chemistry of Protactinium : XI. A Study of the Solvent Extraction of Protactinium(IV) Reduced with Europium(II) from a Perchloric Acid Solution, Using Thenoyltrifluoroacetone as the Extractant(Chemistry)

Abstract

Europium(II) was found to be an excellent reductant for reducing protactinium in microquantities to the tetravalent state. The behavior of Pa(IV) in the perchloric acid solution was investigated by the TTA-benzene extraction method. It was found that the PaOH^ ion existed predominantly in a 0.03-3 M perchloric acid solution at the ionic strength of 3. The reaction of TTA extraction may proceed as : PaOH^+4HA = PaA_4+H_2O+3H^+ or PaOH^+4HA = Pa(OH)A_3(HA)+3H^+ The distribution ratio of Pa(IV) in the system using Eu(II) as the reductant is about ten times as large as that in the system using Cr(II) as the reductant. It was considered that a non-extractable complex may be formed between Pa(IV) and Cr(III), while such a complex may not be formed when Eu(II) is used as the reductant