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  • Author or Editor: Rajendra Swarup x
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Abstract  

The extraction of hexavalent actinides from aqueous carboxylic acid media by tertiary amines was studied. Both U(VI) and Pu(VI) are found to be extracted well whereas Np(VI) was practically inextractable except from acetic acid medium. The absorption spectral studies revealed that the inextractability of Np(VI) is due to its reduction to Np(V). Depending on the diluent used, both tetra and triacetato complexes of U(VI) were found to be present in the organic phase. The absorption spectral studies suggested that the formation of tetraacetato species occurs in the organic phase. An amine extraction method for the separation of U(VI) from a number of metallic impurities using malonic acid medium is suggested.

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Abstract  

The extraction of Np(IV), Pu(IV) and U(VI) from aqueous hydrochloric acid into quaternary amines has been studied. The dependence of the distribution coefficient on amine concentration suggests that the actinide ions extracted are NpCl 6 2− PuCl 6 2− and UO2Cl 4 2− . This is further supported by the absorption spectra of the amine extracts of these actinide ions. Based on the extraction data obtained, a simple method for the separation of typical metal ions such as Cs, lanthanides and Zr from U(VI) and Pu(IV) is suggested.

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Abstract  

Extraction of U(VI) by mixtures of 2-ethylhexyl 2-ethylhexylphosphonic acid (PC88A) and TOPO in cyclohexane and xylene from aqueous sulfuric acid medium has been investigated. Synergism was observed and the species responsible was identified as UO2H2Y4.TOPO. From the data equilibrium constants for the various reaction equilibria at different temperatures and the thermodynamic parameters were calculated. Antagonism was observed when alkylamide or TBP was used as the neutral donor.

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Abstract  

The extraction of U(VI) by mixtures of HTTA and TBP from aqueous thiocyanate medium has been studied. From the data obtained it was observed that the predominant uranium species extracted, causing synergic enhancement in the extraction of U(VI), is UO2(SCN)TTA · 2TBP when benzene and cyclohexane are used as diluents, and that at a very low concentration of TBP the contribution of additional species, viz. UO2(TTA)2 · TBP becomes significant. With chloroform as diluent, however, both of these species are contributing to the synergic enhancement. The extraction of a quaternary uranium species, UO2(SCN)TTA · 2TBP, involving the participation of the aqueous anion is thus established. Equilibrium constants for the various extraction equilibria involved are calculated.

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Abstract  

Solvent extraction and extraction chromatography studies of uranium and plutonium from oxalate supernatant solutions were carried out using 2-ethyl hexyl-2-ethyl hexyl phosphonic acid (PC88A). Based on the distribution data, it was inferred that both the uranium and plutonium could be recovered satisfactorily from such a solution. These studies were found to be useful in optimising the appropriate concentration of PC88A, HNO3, oxalic acid and temperature to recover more than 90% of plutonium from the large volumes of oxalate bearing waste solutions. Spectral characteristics of the extractant and its complexing behavior with U(VI) was also studied using IR & FTIR.

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Abstract  

Ion-exchange studies on uranium and plutonium using macroporous (MP) anion-exchange resins from an aqueous-organic solvent mixed media were carried out to develop a separation method. Out of the several water miscible organic solvents tried methanol and acetone were found to be best suited. Distribution data were obtained for U(VI) and Pu(IV) using three macroporous resins under various parameters. Based on these data, separation factors for Pu/U were calculated. Column experiments using Tulsion A-27(MP) were also carried out. The method has the advantage of loading plutonium from as low as 1M nitric acid in the presence of methanol or acetone and could be used satisfactorily for its recovery from solutions containing plutonium and uranium.

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Abstract  

Crown-ethers extract uranium/VI/, neptunium/IV/ and americium/III/ into MIBK from aqueous thiocyanate solutions. The synergic extraction of U/VI/with crown-ethers and HTTA is also possible.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Charyulu, V. Ramachandhran, Rajendra Swarup, V. Ramakrishna, M. Hanra, V. Venugopal, and B. Mishra

Abstract  

Donnan dialysis and diffusion dialysis techniques are investigated for deacidification and possible concentration of actinide bearing acidic streams. Cation and anion exchange membranes are used in a two compartment dialysis cell to selectively remove acid from americium solutions. Acid concentrations, as high as 8.0M HNO3 are used and the stability of membranes are ascertained. Possibility of simultaneous deacidification and concentration of acidic americium solutions are indicated by combining simple osmosis with diffusion dialysis. All the experiments are carried out under non stirring conditions at room temperature.

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