STABILISATION OF AN ELEMENT AGAINST OXIDATION

摘要

An element (e.g. Pu) is dissolved in a first oxidation state (e.g. as Pu (III)) in a mixed phase system comprising an aqueous nitric acid phase and an organic liquid phase. The element in that state is only partly extractable or is not extractable from the aqueous phase into the organic phase, and is oxidisable in aqueous nitric acid to a higher oxidation state (e.g. as Pu(IV)) in which it is extractable from the aqueous phase into the organic phase. The element is stabilised in its first oxidation state by a substituted urea dissolved in the aqueous phase. Such stabilisation may be used to separate the element from other elements (such as U) which are readily extractable from the aqueous phase into the organic phase in certain oxidation states.