Sulfate system, actinides separation

Pu(VI) ions in the supernatant decrease rapidly to a minimum. They increase then gradually with increasing concentration of ammonium sulfate or hexamminecobalt(III) salt. The precipitation behavior of Pu(VI) ion is similar to that of Pu(IV) ion. However, the concentration of Pu(VI) ions in the supernatant is about 30 times as high as that of Pu(IV) ions when all other conditions are kept the same. In the sulfate system, Pu(IV) and U(VI) ions can be separated from Np(V),Am(III) and Cm(III) ions. Similarly Am(VI) ion can be separated from Cm(III) ion. Thus,at initial concentration as low as 1 mg/mL more than 99% of U(VI), Pu-(IV) and Am(VI) ions can be recovered from the solution. In the sulfate system, hexamminecobalt(III) salt is a separating agent as well as a precipitant of actinide(IV) and (VI) ions. 

III). Figure 5 shows a possible procedure for the separation and recovery of actinides in the sulfate system. 

The purpose of this study was to investigate the anionic exchange behavior of neptunium(V) in sulfate-sulfuric acid, because neptunium is often present as a contaminant during the separation of other actinides (l ). Sulfuric acid systems are seldom utilized in industrial processes, but are often used as part of a laboratory analytical procedure. Literature on neptunium in HC101, HC1, HC1-HF, and HNO3 is quite complete, but the information on the H2S0l system is sketchy at best. There is one report 2) that neptunium(V) is adsorbed strongly on Dowex 2 resin from 0.1 IT to 1 IT H SOip Our measurements indicate that there is very little adsorption of Np(V) on Dowex 1 resin even at low concentrations of sulfate-sulfuric acid. We believe the differences in chemical structure of the two resins are not sufficient to explain the disparity in adsorption. 

---