Iodic acid phosphate

Other reagents can he employed to recover protactinium from uranium refining residues or wastes. For example, treatment with 4M phosphoric or iodic acid precipitates protactinium as phosphate or iodate which is soluble in HF. 

Attempts to characterize the pentavalent iodate obtained by the addition of iodic acid to a solution of protactinium(V) in sulfuric acid (Muxart et al.) have indicated that the product contains a variable amount of iodate (PailOa between 1 0.75 and 1 2.0) and more than twelve molecules of water. The infrared vibration associated with the iodate was observed as a broad band between 600 and 870 cm . The white solid slowly decomposes with the liberation of iodine. The pentavalent phosphate, which precipitates from sulfuric acid solution on the addition of orthophosphoric acid is reported to have the composition Pa0(0H)P04 H20 (Lecloarec and Muxart). Although infrared studies confirmed the presence of the P04 ion it was not possible to unambiguously identify a band due to the Pa=0 group [cf. H3Pa0(S04)3 (19)]. 

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