Interaction of Pu(VI) with Aluminosilicate in Alkaline Solution

Behavior of Pu(VI) in the course of crystallization of aluminosilicate in 2 and 3 M NaOH was studied. Plutonium(VI) inhibits aluminosilicate crystallization. At the Al : Si : Pu molar ratio of 10 : 40 : 2 in the initial mixture, only a minor amount of the X-ray amorphous phase is formed. Partial sorption of Pu(VI) on the aluminosilicate precipitate depends on the alkali concentration in the solution. As determined by spectrophotometry, only neutral and low-charged Pu(VI) hydroxo complexes are sorbed on the aluminosilicate; anionic complexes like PuO₂(OH)₄]^{2 -} formed in more alkaline solutions are not sorbed. Plutonium(IV) formed by reduction of Pu(VI) is sorbed on aluminosilicate from 3 M NaOH.