A preliminary study of the sorption of reduced plutonium (III-IV) onto TiO2 has been done under anoxic conditions at varying pH and ionic strength. The first approach was to study tetravalent Pu, but the sorption decreases with time in this case. This is probably due to disproportionation of Pu(IV) at the TiO2 surface, which then acts as a catalyst. A further observation that supports this explanation is that the sorption of Pu(IV) onto the walls of the experimental equipment is in some cases higher than the sorption of (disproportioned) Pu onto the oxide.
Pu(III) sorption onto the oxide was also investigated and showed similarities with the previously investigated sorption of Pm(III) in a similar system.