THE EXTRACTION OF Am(III) FROM NITRIC ACID BY OCTYL(PHENYL)-N,N-DIISOBUTYLCARBAMOYLMETHYLPHOSPHINE OXIDE - TRI-n-BUTYL PHOSPHATE MIXTURES

Abstract

The extraction behavior of Am(III) from nitric acid by octy1(phenyl)-N,N-diisobutylcarbamoyl methyphosphine oxides, OØDIB]CMPO, in the presence of tributylphosphate, TBP, has been studied using diethylbenzene, decalin, and normal aliphatic hydrocarbon diluents. Relative to ØDIB]CMPO alone, mixtures of TBP and OØDIB]CMPO show a slight enhancement in the extraction of Am(III) from nitric acid solution above 2 M and a moderate decrease in extraction for lower acid concentrations. The net effect of TBP addition to OØDIB]CMPO (as well as other selected carbamoyl methylphosphoryl extractants) is a relative insensitivity of the distribution ratio of Am(III) to HNO₃ concentration in the range of 0.5 M to 6 M and facilitated stripping of Am(III) with dilute acid. Since a continuous variation study of Am(III) extraction using mixtures of ØODIB]CMPO and TBP at a fixed total concentration revealed no evidence of a mixed complex, the TBP appears to be behaving primarily as a phase modifier

The most significant benefit gained from addition of TBP to ØDIB]CMPO is the increased metal ion loading capacity and extractant compatibility with alicyclic and aliphatic diluents. The use of TBP to overcome phase compatibility with other bifunctional extractants of the carbamoylmethylphosphoryl type and the use of other phase modifiers with ØDIB]CMPO have also been investigated.