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  • Author or Editor: D. Bhattacharyya x
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Abstract  

The uptake of Na+, K+, Rb+, Cs+, Ag+, Ca2+, Cu2+, Sr2+, Cd2+, Ba2+, Pb2+, Sc3+, Co3+, Y3+, Sb3+, Tb3+, Zr4+ and Th4+ cations at very small concentrations has been studied over a column of stannic phosphate. The exchanger was prepared by mixing H3PO4, NaCl and SnCl4 in suitable proportions and the ratio of PSn, in the product was obtained to be 1.96. Radiochemical separations of carrier free95Zr from234Th and115mIn, from115Cd have been carried out by adopting a simple chemical procedure over a column of stannic phosphate. The -spectrum analysis showed that the separated products are of high radionuclidic purity. The separation procedures took less than half an hour with quantitative yield.

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Abstract  

Reactions of carbonate radical (CO3 ), generated by photolysis or by radiolysis of a carbonate solution with nickel(II)-iminodiacetate (Ni(II)IDA) were studied at pH 10.5 and ionic strength (I)==0.2 mol·dm–3. The stable product arising from the ligand degradation in the complex is mainly glyxalic acid. Time-resolved spectroscopy and transient kinetics were studied using flash photolysis. From the kinetic data it was suggested that the carbonate radical initially reacts with Ni(III)IDA with a rate constant (2.4±0.4)·106 dm3·mol–1·s–1 to form a Ni(II)IDA species which, however, undergoes a first-order transformation (k=2.7·102·s–1) to give a radical intermediate of the type Ni(II)RNHCHCO 2 ) which rapidly forms an adduct containing a Ni–C bond. This adduct decays very slowly to give rise to glyoxalic acid. From a consideration of equilibrium between Ni(II)IDA and Ni(III)IDA, the one electron reduction potential for the Ni(III)IDA/Ni(II)IDA couple was determined to be 1.467 V.

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Abstract  

Reactions of carbonate (CO 3 –· ) and bicarbonate (HCO 3 · ) radicals generated by photolysis of a carbonate or bicarbonate solution at pH 11.2 and 8.5, respectively, with Co(II) complexes of iminodiacetic acid (IDA) and ethylenediaminetetraacetic acid (EDTA) have been studied. The rate constants for the reactions were in the order of 106–107 dm3mol–1s–1. From the time-resolved spectroscopy of the products formed after reaction of CO –· or HCO 3 · , it is observed that CO 3 –· or HCO 3 · oxidize the metal center to its higher oxidation state.

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Abstract  

The uptake of 22 cations at tracer concentrations has been studied over hydrous tin dioxide exchanger material. A granular variety of tin dioxide was prepared from the reaction of tin(IV) chloride with NaOH solution, and the formula of the material was ascertained to be SnO2·1.7 H2O. Radiochemical separation of carrier-free234Th from238U and113mIn from113Sn was achieved over a tin dioxide column. The separated products were of high radionuclidic purity. The overall separation procedures are very simple and quick with quantitative yield.

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Abstract  

L III edge X-ray Absorption Fine Structure (XAFS) spectroscopic study of Eu(III) sorbed on γ-alumina from aqueous solutions of different pH (values ranging from 6 to 8) has been carried out at XAFS beam line of Elettra Synchrotron facility, Italy, in transmission mode. Extended X-ray Absorption Fine Structure spectra of reference compounds, namely, Eu2O3, Eu(OH)3 and Eu-aquo complex in solution, were also measured. The data were analyzed using the IFEFFIT suite of code. XAFS spectra of the sorption samples is dominated by the Eu–O near neighbor co-ordination at distance 2.4 ± 0.1 Å. 8–9 oxygen atoms, coming from both coordinating water molecule and oxygen atoms from alumina surface, surround the Eu(III) in the surface complex. Next near neighbor atoms in all the sorption samples consist of Al at distance ~3.6 and 3.8 Å, which on comparison with literature data indicates towards Eu(III) bidentate binding to apical oxygen of two different alumina octahedra on γ-alumina surface.

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Abstract  

Application of charged particle activation analysis (CPAA) for the detection of traces of titanium has been demonstrated. Experimental samples containing traces of titanium varying from ppm to ppb levels were prepared by coprecipitating it with aluminium hydroxide, subsequently converted to Al2O3. Titanium in Al2O3 were irradiated with 40 MeV -particles in the Variable Energy Cyclotron, Calcutta. The element was detected through the product radioisotopes,48V,47Ca,47Sc,51Cr,49Cr and48Cr, produced from various nuclear reactions such as (, pxn), (, xn), etc. Suitability of Al2O3 as diluent matrix for the element has been verified.

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Abstract  

Ethyl-substituted bis-triazinylpyridine (Et-BTP), a nitrogen containing soft-donor extractant, was used in investigations pertaining to the separation of Am3+ and Eu3+ from dilute nitric acid feed solutions by extraction chromatography using XAD-4 as the inert support, chlorinated dicarbollide as the modifier and 2-nitrophenyloctylether (NPOE) as the diluent. After carrying out a series of experiments, the optimum composition of the extractant mixture for the resin was found out to be 0.1 M Et-BTP and 0.025 M CCD in NPOE. Separation factor values were encouraging to carry out subsequent batch uptake studies at varying nitrate ion concentration which indicated favourable separation behaviour up to NaNO3 concentration of 2 M. Column studies have been carried out and conditions for elution and separation of Am3+ from Eu3+ have been found out. Long term stability of the resin was also investigated.

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Abstract  

The iron bearing phases present in a ferromanganese nodule from the Central Indian Ocean have been determined using57Fe Mössbauer spectroscopy. The Mössbauer results have been corroborated by XRD, IR and TG-DTA studies. The Mössbauer spectrum of a ferromanganese nodule shows a broad line width which indicates the presence of more than one iron bearing paramagnetic oxide or oxyhydroxide phases where iron is present as Fe3+. -FeOOH has been distinctly characterised as one of the iron bearing phases in the nodule. Other oxyhydroxide and oxide phases of iron in the nodule have been ruled out. A typical paramagnetic doublet persists even at very high temperature which has been proposed to be due to iron(III)phosphate. Formation of solid solution of Mn2O3–Fe2O3 has been observed in the heat treated nodule at 1073 K, which has been characterised by the Mössbauer technique.

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