Rajendra Swarup

Extraction of actinides by long-chain amines—I: Extraction of Np(IV), Np(V), Np(VI), Pu(VI) and U(VI) by TLA and Aliquat-336

Abstract The extraction of Np(IV) into tricaprylmethyl ammonium nitrate (Aliquat-336) and Np(V), Np(VI), Pu(VI) and U(VI) into TLA and Aliquat-336 from nitric acid medium was investigated. The absorption spectra of Aliquat-336 extracts containing Np(IV), Pu(IV), Np(VI) and Pu(VI) were obtained to know the species of these ions present in the amine.

Recovery of americium from nitric acid solutions containing calcium by different co-precipitation methods

Recovery of americium from nitric acid solutions was studied by co-precipitation as hydroxide with various ions like calcium, ferric, nickel using sodium hydroxide and ammonium hydroxide. Studies were also carried out to recover americium using lanthanum fluoride and bismuth phosphate co-precipitation. All the methods are able to co-precipitate Am quantitatively. However, co-precipitation of Am with optimum concentration iron using ammonia is found to be better from nitric acid solutions containing large concentrations of calcium ions. Approximately 2 g of Am was recovered from 150 litres of solution batch wise using iron.

Some studies on the extraction of actinides with crown-ethers

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.

Synergistic extraction of hexavalent actinides by HTTA and neutral donors—I: U(VI)-HTTA-TBP-benzene system

The synergistic extraction of U(VI) from aqueous nitric acid by mixtures of HTTA and TBP was studied to establish the presence of mixed ligand species, using a method-developed in this laboratory. The results obtained by this method were corroborated with the conventional extraction studies. It was established that the species UO2(NO3)(TTA)TBP reported in the literature was not involved in the synergistic extraction and that the only species responsible for synergism was UO2(TTA)2·TBP. Equilibrium constants for various equilibria involved are calculated.

Extraction of U(VI) by phosphonic acid in the presence of neutral donors

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.

Solvent extraction studies of americium(III) using saponified acidic organophosphorous extractants

Abstract A systematic study on the extraction of Am(III) from aqueous nitric acid medium using saponified organophosphorous extractants 2-ethylhexyl 2-ethylhexyl phosphonic acid (PC88A) and di-2-ethylhexyl phosphoric acid (HDEHP) has been carried out. The distribution data obtained for Am(III) showed significant increase in the values with saponified extractants. The studies carried out with variation of parameters such as HNO 3 concentration and percentage saponification of organic extractants revealed that Am(III) could be quantitatively extracted from aqueous nitric acid medium by choosing the proper saponification of the extractants. An attempt has been made to derive the mathematical models for the extraction behaviour of Am(III) with these extractants.

Separation of Uranium and Plutonium from an Aqueous Solution Containing Phosphoric, Sulfuric, and Nitric Acids by Solvent Extraction

A solvent-extraction method has been developed to separate uranium and plutonium from an aqueous solution containing phosphoric, sulfuric, and nitric acids by extracting them into 0.5 M TOPO in xylene followed by stripping with ammonium carbonate solution. In the case of plutonium, spectral evidence reveals that the complex species extracted into TOPO is predominantly the neutral nitrate complex of Pu(IV).

EXTRACTION OF ACTINIDES BY QUATERNARY AMINES FROM HYDROCHLORIC ACID MEDIUM

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 NpCl62− PuCl62− and UO2Cl42−. 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.

An electrocatalyzed process for leaching of plutonium from active Gauntlets and subsequent separation by solvent extraction

An electrocatalyzed process has been described for the dissolution of plutonium from the contaminated neoprene gauntlets used during the fabrication of plutonium-bearing fuels. Agents Ag(II) and Ce(IV) were used as catalysts. The results indicated that it was possible to leach out plutonium satisfactorily from such contaminated neoprene gauntlets. The problems involved in processing with Ag(II) and the limitations of the process are also discussed. Further, plutonium was separated from the leached solution by solvent extraction using di-2-ethylhexyl phosphoric acid as the extractant.

Synergic extraction of thorium by beta-isopropyltropolone-neutral donor combinations

The extraction of thorium by benzene solutions of HIPT in presence of different neutral extractants (S) was studied using perchloric, hydrochloric and sulphuric acids as aqueous media. With TBP as the donor the effect of the diluents CCl4, benzene and CHCl3 on the extraction was studied. The synergism observed was attributed to the formation of the extractable adduct Th(IPT)4 · S and, in some cases, to the extraction of additional mixed adducts involving the participation of the anion of the aqueous medium used for extraction. The adduct formation constants for the formation of Th(IPT)4 ·S were evaluated and the formation of this adduct was independently confirmed by spectrophotometric measurements. The aqueous complexing of thorium by IPT was investigated spectrophotometrically as these data were required for the quantitative interpretation of the extraction data.