SEPARATION AND RECOVERY OF PLUTONIUM FROM OXALATE SUPERNATANT USING CMPO

A simple and efficient procedure has been developed to quantitatively recover Pu from oxalate supernatant using a mixture of tyl(phenyl)-N,N -diisobutylcarbamoylmethylphosphine oxide (CMPO) and TBP in dodecane. Pu(IV) in the range of 6.9 to 34.6 mg/l was quantitatively extracted i nto 0.2M CMPO + 1.2 M TBP in dodecane from an aqueous solution contain ing 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 M TBP has shown a dramatic increase in the D values, being 0.3 at 1.0 M and >10( 4) at 7.5 M. The extraction was almost quantitative even at the aqueou s to organic ratio of 10:1. Plutonium could be quantitatively recovere d,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. Approximately 92% of the Pu was found in th e precipitate and approximately 7% in the supernatant. Using this proc edure, Pu in a concentrated form (approximately 50 times), could be re covered from the oxalate supernatant solutions without recourse to the destruction of oxalate ion. The slope of 2 from the plot of log D vs log [NO3-] and log [CMPO] respectively suggest the species in the orga nic phase to be PuC2O4(NO3)2.2CMPO. The absorption spectral study of P u(IV) confirmed the above observations.