Separation of actinoid(III) and actinoid(IV) by solvent extraction and adsorption

Abstract

The extraction of americium(III) and thorium(IV) by thenoyltrifluoroacetone (TTA) and dibenzoylmethane (DBM) and the adsorption of the ions on silica gel were studied so as to develop a method for the separation of plutonium(III) and plutonium(IV) in natural waters. When the aqueous phase was free from strong complexing anions, the separation of americium(III) and thorium(IV) was possible by the TTA and DBM extraction methods in the pH ranges 1–2.5 and 3–6 respectively and they were roughly separated by the silica gel adsorption method. However, 0.03 M sulphate solution interfered with the separation by the adsorption method and shifted the suitable pH range for the separation by solvent extraction. Fluoride ion may also affect the extraction and adsorption, judging from its complex formation constant with actinoid(IV). The concentrations of complexing anions should be considered for the separation of actinoid(III) and actinoid(IV) in natural waters.