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  • Author or Editor: S. Bhattacharyya x
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Abstract  

A method has been described for the isolation of radiochemically pure140La from140Ba. The tracer140Ba−140La is mixed with 6M LiNO3 solution to make an anionic complex. The solution is then fed into a column (1 cm×0.4 cm) of Kieselguhr impregnated with Aliquat-336.140La is adsorbed in the column while140Ba is eluted with 6M LiNO3. After complete removal of140Ba,140La is eluted with 0.002M HNO3 solution. The purity of140La is established by both its half-life and γ-spectrum.

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Abstract  

Radiochemical separations of carrier-free210Bi and UX1 activities from210Pb and U, respectively, have been carried out using a silica gel column.210Pb was adsorbed in the column as molybdate and210Bi passed unadsorbed. Lead activity was next removed with 25 ml of 0.1 M HNO3. In the case of separation of UX1, the coloured carbonate complex of U was removed from the silica surface by washing with saturated sodium carbonate solution, keeping UX1 retained, and finally UX1 was washed out with 25 ml of conc. HNO3. Studies of the beta decay of210Bi and the γ-spectrum analysis of UX1 has shown that the separated products in both cases are of high radiochemical purity. The processes in each case took less than one hour and the yield was satisfactory.

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Abstract  

A simple solvent extraction procedure for an effective separation of traces of tantalum from rock phosphate samples has been developed and used in its determination through neutron activation analysis. The tantalum contents in the samples were found to be about 3.10−7%.

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Abstract  

Studies on the distribution of various oxidation states of recoil sulphur formed by35Cl(n, p)35S reaction in the alkali halides, namely, NaCl, KCl and RbCl have been made. A suitable anion exchange method using Amberlite IRA-410 in the chloride form has been described for rapid separation of the various radiosulphur species. The elution was carried out by means of nitrate solutions. The observed results on the effect of cation environment in affecting the distribution of radioactive sulphur amongst its various oxidation states were discussed on the basis of electron affinity and ionic size of the metal ion in question.

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Abstract  

Zirconium phosphate as ion exchanger suitable for column operation has been prepared by mixing hot metaphosphoric acid solution with a solution of zirconium oxychloride when the white insoluble phosphate separated out which was dried and purified. The ratio of zirconium: phosphate was found to be 1:2. Separation of parent-daughter systems like115Cd-115mIn,144Ce-144Pr and210Pb-210Bi were carried out with this exchanger. γ-ray spectrum of the separated115mIn and the β-decay curve of144Pr and210Bi showed that all the daughter activities are radiochemically pure. The separation process in each case takes less than half an hour and the yield is quantitative.

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Abstract  

A new way of radiochemical separation of carrier-free115mIn from115Cd and132I from132Te over the column of zirconium oxide is described. Activities of Cd and In in equilibrium in dilute acetic acid solution were bufferred with dilute sodium acetate and fed into the column at a pH 7, when cadmium activity passed out unadsorbed and the115mIn was adsorbed in the column. A study of the γ-ray peak of the separated115mIn showed that the product is of high radionuclidic purity. Te-I pair was separated by passing the weakly acidic solution of132Te and132I in the presence of AgNO3 and Na2SO3, through the column where both activities were adsorbed. Iodine was washed outh with 5% sodium thiosulphate solution and the retained tellurium activity was later washed out with 6M HNO3. The β-decay study showed that the separated132I product is of high radiochemical purity. The processes took less than half an hour and the yields were quantitative.

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Abstract  

A radiochemical procedure for separation of carrier-free22Na from bulk of Mg is described. The method involves the initial removal of bulk of Mg as Mg(OH)2 by means of ammonia followed by separation of the last traces of Mg by means of extraction with a cationic liquid exchanger, di-(2-ethylhexyl) phosphoric acid (HDEHP) in cyclohexane.

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Abstract  

A new stable chelating resin was synthesized by incorporating 2-aminothiophenol into Merrifield polymer through C-N covalent bond and characterized by elemental analysis, IR and thermal study. The sorption capacity of the newly formed resin for Hg2+ as a function of pH has been studied using 203Hg radioisotope. The resin exhibits no affinity to alkali or alkaline earth metal ions and common anions. The separation of mercury(II) in presence of different alkali and alkaline earth metal ions (Na+, K+, Mg2+, Ca2+, Sr2+, Ba2+), common anions (ClO4 , SO4 2−) and other diverse ions (Ag+, Cu2+, Pb2+, Fe3+, Ni2+ and Zn2+) has been checked. In column operation it has been observed that Hg2+ content of the waste water can be removed at usual pH of natural water. Mercury was determined by isotope dilution method and the concentration of Hg2+ in the waste water spiked with 203Hg was found to be 0.05 to 0.09 μg/ml.

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Thermal characteristics of the vanadates of zinc, manganese and silver have been studied by DTA and TG techniques and the different transition products thus obtained have been characterised by IR, X-ray diffraction and magnetic susceptibility data. Chemical analyses indicate the following compositions of these vanadates: (1) Zn2V2O7.5H2O, (2) Zn3(VO4)2.3H2O, (3) Mn(VO3)2.2H2O and (4) Ag3VO4. The DTA curves indicate that zinc pyrovanadate undergoes endothermic changes at 110–195, 265, 365, 440, 660° and one exothermic change at 485°. This system is diamagnetic which becomes completely paramagnetic after 660°. Zinc orthovanadate exhibits a number of endothermic peaks at 300, 470, 700, 815 and 930° respectively. This system is feebly paramagnetic and retains this property up to 930°. Manganese metavanadate undergoes endothermic changes at 240, 280–590, 830 and 880° respectively. This vanadate is paramagnetic and paramagnetism increases appreciably at 590° and remains constant up 830°. Silver orthovanadate exhibits three endothermic changes at 180, 455 and 640°, respectively.

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Abstract  

A set of experiments was conducted in an HEL thermal screening unit with synthetic mixtures of raw materials in various proportions to evaluate the potential thermal hazards at normal and offset process conditions for nitration of symmetrical trichlorobenzene (TCB). The experiments were carried out in the adiabatic condition. The onset temperatures of the exotherms along with maximum temperature and pressure rise data for the desired and undesirable reactions were obtained. In the presence of excess nitric acid and oleum, the reaction shows a severe thermal runaway at the onset temperature of 138C with a rapid rise in temperature and pressure leading to a potential explosion.

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