The Chemistry of Protactinium. II. The Behavior of Pentavalent Protactinium in a Perchloric Acid Solution

Studies of the chemical behavior of protactinium(V) were carried out with the TTA-benzene extraction method, the ion exchange method and the filtration method. When the protactinium concentration is less than 10−6 m and the perchloric acid concentration is 0.3—2.0 n, the reaction of TTA extraction may proceed as: PaOm(OH)n5−2m−n+4HT(OH)T4+(m+n−1)H2O+(5−2m−n)H+ where 2m+n is 3 and 4, or as: PaOm(OH)nT4−2m−n+4HT5+(m+n)H2O+(4−2m−n)H+ where 2m+n is 2 and 3. The cation exchange experiment gives results consistent with this conclusion. On the other hand, when the concentration of protactinium is higher than 10−6 m, the above relation does not hold, even in the 5 n perchloric acid solution, because protactinium forms the aggregates to a great extent. This has been confirmed by the filtration experiment.