Extraction of Np(IV), Np(VI), Pu(IV) and U(VI) with Amides, BEHSO and CMPO from Nitric Acid Medium

Abstract

The extraction of Np(IV), Np(VI), Pu(IV) and U(VI) from a nitric acid medium has been carried out with dibutyldecanamide (DBDA), dihexyldecanamide (DHDA), bis-2-ethylhexylsulphoxide (BEHSO) and octyl(phenyl)-N-N-diisobutyl-carbamoylmethylphosphine oxide (CMPO) using n-dodecane as the diluent. The order of extraction for the metal ions is CMPO> BEHSO>DHDA>DBDA. The species extracted into the organic phase was found to be the disolvate with all the extractante while using hexavalent metal ions Np(VI) and U(VI) and also with tetravalent ions Np(IV) and Pu(IV) in the case of BEHSO and CMPO. However, in the case of DBDA and DHDA, Np(IV) and Pu(IV) were extracted as the trisolvate species. The equilibrium constant (K) for the formation of the above species has been evaluated after applying the possible correction factors. In general, log A" increases with increasing basicity of the extractants. In the case of amides, the plot of log A -verses k H (acid uptake equilibrium constant) gave straight lines which could be represented by the empirical equation : logici) = 5.17 k H + 0.18 and log = 3.11 k H + 1.81 for the respective metal ions. With the help of these empirical equations it is possible to predict the equilibrium constant values of amide complexes of U(VI) or Pu(IV) if the k H values of amides are known. The solid complexes of U(VI) with DHDA and CMPO were synthesized and characterized by elemental analysis and IR spectra. Two molecules of DHDA and only one molecule of CMPO are bound with U(VI). The bidentate nature of CMPO in its solid species has been confirmed.

Summary Report on Gamma Radiolysis of TBP/n-dodecane in the Presence of Nitric Acid Using the Radiolysis/Hydrolysis Test Loop

“…The measured values of D Pu as a function of nitric acid concentration agree well with previous literature reports. [7][8][9][10] The flowsheet shown in Figure 7 (vide supra) is employed to evaluate the extraction behavior of Pu-239 radiotracer using the TBP solvent samples generated in this study. The results of the flowsheet tests for solvent irradiated in the presence of 0.9 M, 1.4 M, and 3.0 M HNO 3 are presented in Tables 2 -4, respectively.…”

Redox behavior of gas phase Pu(IV)-monodentate ligand complexes: an investigation by electrospray ionization mass spectrometry

“…The actinide ions, such as Pu(IV) preferentially bind with oxygen donor ligands. They are well extracted by the ligand tri-n-butylphosphate (TBP) used in the industrial PUREX process [1,2] as well as by N,N-dialkylamides [3][4][5][6][7][8][9]. Indeed dialkylamides have been under study as potential candidates for plutonium extraction since the 1960's [10].…”

“…Indeed dialkylamides have been under study as potential candidates for plutonium extraction since the 1960's [10]. Some advantages monoamides offer over TBP include the ability to easily remove degradation products from the solvent stream, their complete incinerability [3,9,11], and the important influence of the alkyl groups R, R 0 , and R 00 on the extraction of Pu(IV) [4,5,7,9,[11][12][13][14].…”

“…The affinity for Pu(IV) extraction by N,N-dialkylamides strongly depends on the structure of the amide, especially the structure of the alkyl group on the carbonyl carbon [4,5,[12][13][14]. In this study, three monoamides were selected to better understand the effect of structure on the stability of the Pu-monoamide ion: Fig.…”

Redox Behavior of Neptunium(V) in Tributyl Phosphate and N,N-Dihexyl Octanamide Extractants Dissolved in n-Dodecane

“…The stoichiometries of the extracted Np(IV) and Np(VI) species with DHOA were determined to be Np(NO 3 )] 4 ·3DHOA and NpO 2 (NO 3 ) 2 ·2DHOA, respectively [14,15]. Both TBP and DHOA extracted more Np(VI) than Np(IV), i.e.…”