Extraction of actinides by Tri-n-butyl phosphate derivatives: Effect of substituents

Tri-n-butyl phosphate (TBP) is most extensively used extractant in the nuclear fuel cycle. The present work investigates the effect of substituents and their role in the basicity of organophosphorus extractant on the uptake of actinides. In this connection, we have synthesized six different analogues of TBP by altering one of its butoxy group. The synthesized TBP derivatives were well characterized and evaluated for their solvent extraction behavior towards U(VI), Th(IV), Pu(IV) and Am(III), as well as acid uptake as a function of nitric acid ranging from 0.01 to 6 M and the data provides the comparison of their extraction behavior with that of 30% (1.1 M) tri-n-butyl phosphate under identical conditions. It was observed that distribution coefficient values strongly depend on the nature and size of the substituents. The presence of electron donating groups enhances the uptake of the actinides and the distribution coefficient values were significantly larger as compared to that of TBP. In addition, the effect of sodium nitrate on the extraction of uranium and enthalpy of extraction were also studied and revealed that the extraction process was exothermic. (C) 2017 Elsevier B.V. All rights reserved.