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  • Author or Editor: M. Nagar x
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Abstract  

The determination of carbon, hydrogen, nitrogen, fluorine, chlorine and sulphur contents for characterization of plutonium complexes with organic ligands have been standardized and glove box adopted. Various plutonium(IV) mono- and di-carboxylates, plutonium(IV) chelates with pyrazolones, UO 2 ++ and PuO 2 ++ complexes having pyrazolones as chelating agent and sulfoxides, amides and phosphine oxide ligands as oxodonors; uranium carbides and uranium nitrides and several potential organic extractants for actinides were analyzed satisfactorily. All these methods set up in double module glove box train are extremely useful for a low budget radioactive laboratory engaged in research in solid actinide complexes.

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Abstract  

The precipitation behaviour of basic plutonium(IV) compounds from dilute nitric acid medium with aliphatic dicarboxylic acids has been investigated. Unlike plutonium(IV) oxalate, which is precipitated in acid medium (1–4M), the higher dicarboxylates precipitate in 0.9–2.5 pH range and their elemental analysis indicate Pu/dicarboxylate ratio of 11. The mode of formation, composition, solubility and thermal degradation behaviour for plutonium(IV) hydroxosuccinate has been studied. The hydroxy group determination by kinetic titration using fluoride complexing revealed that the compound has a Pu:OH ratio of 11 and determination of bridging oxygen group gave a Pu:O ratio of 10.5 suggest its formation as hydroxysuccinate having an oxobridged formula.

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Abstract  

Solvent extraction behaviour of Am(III) from dilute nitric acid media with sulfoxides (R2SO) in Solvesso-100 has been investigated over a wide range of conditions. Very poor extractability of Am necessitated the use of salting-out agents, viz., nitrates of Al, Mg, Ca, Li and NH 4 + . Effects of certain variables such as acidity, extractant concentration, saltingout agent, temperature etc., on metal extraction by sulfoxides have been examined systematically. For a fixed sulfoxide concentration, extraction attains a maximum value up to around 0.2–0.4M HNO3 and decreasing above 1M HNO3. In contrast, increasing the concentration of sulfoxide (0.8M DISO, 1.3M DBuSO) gives almost quantitative Am extraction up to 1M HNO3. For satisfactory extraction, di-n-octyl as well as di-n-hexyl sulfoxide are the most suitable extracting agents. Extractability of Am increases with increasing amounts of all the salting-out agents studied and their effect follows the sequence: Al3+>Mg2+>Ca2+>Li+>NH 4 + ; this is also the relative dehydrating effect of the cations. The species extracted would appear to be Am(NO3)3.3R2SO. Americium is easily stripped with 1–3M HNO3 solutions from the loaded organic phase. Extraction decreases with increasing temperature, indicating the extraction to be exothermic. Extraction from partially non-aqueous solutions was also investigated.

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Abstract  

Solid complexes of plutonylion with benzoyl (PMBP), acetyl (PMAP) and trifluoroacetyl (PMTFP) derivatives of 1-phenyl-3-methylpyrazol-5-one and various oxo donors such as dihexyl sulfoxide (DHSO), dioctyl sulfoxide (DOSO), dibutyl hexanamide (DBHA), dibutyl octanamide (DBOA) and dibutyl decanamide (DBDA) have been synthesized and characterized. Analytical data establish that sulfoxides form 11 adducts and have the stoichiometry PuO2·X2·Y (X=PMBP, PMAP and PMTFP) and Y=DHSO and DOSO while amides form 12 adducts of the type PuO2X2·2A where A=DBHA, DBOA and DBDA. The I. R. spectra of sulfoxide and amide complexes indicate that the ligands are O-bonded. Spectrophotometric investigations of the benzene solution of these complexes indicate a bathochromic shift of the 831 nm peak to 848–853 nm region, which confirms the retention of PuO 2 2+ moiety in these synergistic adducts.

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Abstract  

Plutonium/IV/ compounds obtained in the reactions with phenylacetic acid and -naphthyl acetic acid in the pH range of 3.5–5.0 have been isolated and studied. Carbon, hydrogen and plutonium analyses have shown that plutonium/IV/ phenyl acetate and plutonium/IV/ -naphthyl acetate have the composition Pu/OH/3/C10H7CH2COO/, respectively. Infra-red and ultra-violet absorption spectral studies and thermogravimetric analysis have corroborated these chemical formulas.

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Abstract  

The extraction behavior of uranium(VI), plutonium(IV) and fission products like zirconium, ruthenium and europium from 3.5M nitric acid medium with gamma-irradiated dibutyl derivatives of hexanamide (DBHA), octanamide (DBOA) and decanamide (DBDA) in dodecane has been investigated as a function of absorbed dose up to 184 MRads. The results indicate that the Kd value for extraction of uranium(VI) decreases gradually, while Kd for extraction of plutonium(IV) decreases rapidly with dose up to 35 MRads, increasing thereafter with dose, indicating synergistic effects of radiolytic products at higher doses. Ruthenium and europium are not extracted in the entire dose range up to 184 MRads, while extraction of zirconium(IV) increases steadily up to 50 MRads and increases radiply thereafter, indicating synergistic effect of radiolytic products similar to that of plutonium(IV) beyond a dose of 50 MRads. The extractability of uranium(VI) and plutonium(IV) with 1M dibutyl decanamide (DBDA) in dodecane was studied for uranium loading up to 75 mg/ml and plutonium loading up to 3 mg/ml. The percent extraction was found to vary from 91 to 71 for uranium and 95 to 89 for plutonium, respectively. Quantitative stripping of uranium can be achieved with 0.01M nitric acid and plutonium with 0.5M nitric acid and 0.05M hydroxylamine soluton in two steps from an organic phase loaded with 53.2 mg/ml of uranium.

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Abstract  

A method is described for the estimation by infrared spectrometry of some organic extractants such as tributyl phosphate (TBP), dioctyl sulfoxide (DOSO) and dibutyl decanamide (DBDA), which have importance as solvent extractants for fuel reprocessing. Measurements have been carried out using their characteristic donor peaks. Results indicate that Beer's law is obeyed in the concentration range of 0.01 to 0.2M with an optimum around 0.1M. The estimations have also been carried out by measuring the intensities of the OH stretches of the donor hydrates, which are very useful in estimating these donors in solvent extracted species. The method has been successfully applied to the determination of amide contents of irradiated dialkylamides.

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Abstract  

The extraction behavior of uranium(VI), plutonium(IV) and some fission products like zirconium, ruthenium and europium from 3.5M nitric acid with -irradiated dibutyl (DBEHA), di-isobutyl (DIBEHA), methylbutyl (MBEHA) derivatives of ethylhexylamide and di-isobutyl octanamide (DIBOA) in n-dodecane has been investigated as a function of absorbed dose up to 184 Mrad. The results indicate that the Kd values for extraction of uranium(VI) decreases gradually up to 45 Mrad and becomes almost constant beyond this dose up to 184 Mrad, while extraction of plutonium(IV) increases rapidly beyond a dose of 45 Mrad due to synergistic effect of the radiolytic products formed at higher doses. The extraction of zirconium(IV) increases gradually up to 45 Mrad and attains a limiting value at higher doses. Ruthenium and europium are not extracted in the entire dose range studied. Infrared studies confirm the final products of radiolysis as the respective amines and carboxylic acids. Radiolytic degradation of the pure amides was determined by estimating the residual amide contents using quantitative IR spectrometry and were found to follow the order DIBEHA > DBEHA > MBEHA > DIBOA.

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Abstract  

Almost quantitative recovery of plutonium from assorted non-recoverable aqueous acidic and organic waste solutions originating from solvent extraction studies and synthesis of solid plutonium compounds has been achieved by using combined solvent extraction and extraction chromatographic techniques. During solvent extraction a mixture of 0.2M CMPO+1.2M TBP in dodecane was used as the extractant while in extraction chromatography a small column of CMPO adsorbed on Chromosorb-102 (CAC) was utilised. The activities could finally be recovered from the loaded organic phase as well as the CAC column. The effluent after the combined operation was almost alpha-free. About 3 g of plutonium was recovered from about 19 litres of different wastes.

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Abstract  

Extraction of uranium(VI) and plutonium(IV) has been studied with N,N-dibutyl derivatives of hexanamide (DBHA), octanamide (DBOA) and decanamide (DBDA) at various fixed temperatures of 20, 30, 40 and (50±0.1)°C. The equilibrium constants for the uptake of nitric acid (Kh, a measure of their relative basicities) by these amides were evaluated by the usual method. The equilibrium constants for the extraction of uranium as well as plutonium with all the three amides follow their order of basicity (Kh) viz. DBHA (0.09)<DBOA (0.10)<DBDA (0.13) with log K values of 1.31, 1.43 and 1.73 for uranium and 3.55, 3.65 and 4.17 for plutonium, respectively. It has been observed that whereas uranium(VI) is extracted as a disolvate (similar to TBP and sulfoxides), plutonium(IV) has been found to be extracted as a trisolvate. The thermodynamic parameters evaluated by the usual temperature coefficient method indicate that the extraction reactions of uranium as well as plutonium are stabilized by negative enthalpy change only.

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