K. Venugopal Chetty

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.

EXTRACTION OF PLUTONIUM (III) BY TBP IN PRESENCE OF URANIUM

ABSTRACT The distribution ratio (D) values for the extraction of plutonium (III) from nitric acid medium into 30% TBP in n-dodecane saturated with uranium(VI) (0% to 80%) were determined. For a fixed saturation of TBP with uranium, the D values for Pu(III) were found to increase with increase in nitric acid concentration (1M to 5M). At a fixed nitric acid concentration, the D values were found to decrease with increase in loading of TBP with uranium. The D values for the extraction of Pu(III) using 20% TBP in n-dodecane and 30% TBP in n-paraffin at 80% uranium saturation were also determined The distribution data was least squares analysed against concentration of HNO3 as well as percentage saturation of TBP with uranium and the coefficients obtained are reported. For all these extraction systems, D values for U(VI) were also determined.

Synergic Extraction of Uranium(VI) from Different Aqueous Media Using HTTA and Neutral Donors

The extraetion of uranyl ion from aqueous nitrate, Perchlorate and thiocyanate medium with 2-thenoyl trifluoroacetone (HTTA) and N,N-disecbutyl pentanamide (DBPA) has been studied to know the extracted U(VI) species. It is established that the U(VI) species responsible for synergism is U02(TTA)2 • DBPA when aqueous medium is nitric acid. With aqueous thiocyanate medium, the predominant U(VI) species extracted is U02(NCS) (TTA) • 2 DBPA. The synergic extraetion of U(VI) from aqueous Perchlorate medium using HTTA in combination with a bifunctional neutral organophosphorus extractant, DBDECMP has also been studied. The U(VI) species responsible for the synergism is found to be U02(TTA)2 • DBDECMP. Equilibrium constant values for the various extraetion equilibria involved are calculated.

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.

Solvent extraction of Hf(IV) from mixed electrolyte solutions into di-2-ethylhexylphosphoric acid (HDEHP)

Extraction of hafnium(IV) from aqueous sulfuric and sulfuric-nitric acid solutions into di-2-ethylhexylphosphoric acid (HDEHP) in xylene has been investigated. The Hf(IV) species extracted from 5M sulfuric acid was found to be HfY2(HY2)2 where Y and HY2 represent the anions of monomeric HY and dimeric H2Y2 forms of HDEHP, respectively. In the presence of nitrate ion the species extracted are found to be Hf(NO3)Y(HY2)2 and Hf(NO3)2)(HY2)2. But when the aqueous phase is 3.0M HNO3+2.5M H2SO4 only one species, Hf(NO3)2(HY2)2 was extrated. No synergism was observed from 5M H2SO4 by HDEHP with the addition of thenoyltrifluoracetone (HTTA).

Homogeneous isotope exchange between copper(II) and bis(resacetophenone oxime)copper(II) complex

Isotope exchange behavior of bis(resacetophenone oxime)copper(II) complex with copper(II) in tri-n-butyl-phosphate and methanol medium has been studied. The studies were carried out at different temperatures varying the concentration of both metal ion and complex. The results show that the complex is labile in the kinetic sense. Increase in temperature increases the isotope exchange rate. The increase in concentration also results in enhancement of the rate of reaction.

HOMOGENEOUS ISOTOPIC EXCHANGE BETWEEN NICKEL(II) AND BIS(RESACETOPHENONE OXIME) NICKEL(II) COMPLEX

Isotopic exchange behaviour of bis(resacetophenone oxime) nickel(II) complex with nickel(II) in tri-n-butyl phosphate (TBP) and ethanol medium has been studied. The studies were carried out at different temperatures by varying the concentrations of both metal ion and the complex. Experimental observations showed that the complex is kinetically labile. Increase in temperature increases the isotopic exchange rate. Increase in concentration of either metal ion or complex results in significant increase of the reaction rate.

Effect of mixed solvent media on the sorption and separation of uranium and plutonium on macroporous resins

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.

EXTRACTION OF U(VI) AND PU(VI) FROM HCLO4 BY HDEHP AND SYNERGISM WITH TOPO

The extraction behaviour of U(VI) and Pu(VI) by di-2-ethylhexylphosphoric acid (HDEHP) from perchloric acid was investigated. The actinide species were extracted as M02(HY2)2, where HY2 represents the anion of the dimeric HDEHP(H2Y2). Addition of tri-n-octylphosphine oxide (TOPO) to H2Y2 enhanced the extraction of both U(VI) and Pu(VI). This behaviour is attributed to the adduct M02(HY2)2 · TOPO and due to the mixed complex M02C104(HY2) · TOPO containing anion from the aqueous perchloric acid.

Homogeneous isotopic exchange between nickel(II) and bis(diethyldithiocarbamato)nickel(II) complex

Isotopic exchange behaviour of bis(diethyldithio carbamate) nickel(II) complex with nickel(II) in chloroform and methanol medium was studied. The studies were carried out at different temperatures varying the concentration of both metal ion and the complex. The results show that the complex is labile in the kinetic sense. Increase in temperature increases the isotopic exchange rate. The increase in concentration also results in enhancement of the rate of reaction.