Publication

Abstract : A s imp1e and efficient procedure has been developed to quantitatively recover Pu from oxalate supernatant using a mixture of octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) and TBP in dodecane. Pu(IV) in the range of 6.9 to 34.6 mg/1 was quantitatively extracted into 0.2M CMPO + 1.2 M TBP in dodecane from an aqueous solution containing 3.0 M HNO3 and 0.1 M H2C2O4. At such low concentrations of Pu, the distribution ratio (D) did not change but the increase in oxalic acid concentration drastically reduced these values. The variation in HNO3 concentration at a fixed concentration of 0.2 M CMPO + 1.2 N TBP has shown a dramatic increase in the D values, being 0.3 at 1.0 M and 104 at 7.5 M. The extraction was almost quantitative even at the aqueous to organic ratio of 10:1. Plutonium could be quantitatively recovered by (i) stripping with 0.5 M acetic acid and (ii) coprecipitating it directly from the organic phase with 0.3 M oxalic acid + 0.3 M calcium nitrate + sodium nitrite. ∼92% of the Pu was found in the precipitate and ” ∼7% in the supernatant. Using this procedure, Pu in a concentrated form ( ∼50 times), could be recovered from the oxalate supernatant solutions without recourse to the destruction of oxalate Ion. The slope of 2 from the plot of log D ve log [NO3 −] and log [CMPO] respectively suggest the species in the organic phase to be PuC2O4(NO3)2. 2CMPO. The absorption spectral study of Pu(IV) confirmed the above observations.