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  • Author or Editor: S. Mishra x
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Abstract  

The adsorption of mercury(II) on potassium titanate has been studied in chloride media at different pH values, adsorbate concentrations and temperatures. Effect of different ligands and acid concentrations on the uptake was also investigated. Desoprtion studies were also done to check the reversibility of the process. Interestingly a more or less constant and high value of adsorption has been found at different temperatures, pH values and concentrations and a decrease in the uptake with an increase in the bulk acid concentration was observed.

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Abstract  

Synergism is observed in the extraction of thorium(IV) by the binary mixture of PC88A and TOPO in the range 0.1–2.5M HNO3 solution. The increase in acidity decreases the synergistic effect. Antagonism is observed when the extraction is carried out in H2SO4 medium.

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Abstract  

An attempt js made to study the behaviour of recoil128I atoms in neutron irradiated I2O5 at ambient temperature. The initial retention is found to be 44±2%. However, a substantial increase /57±2%/ in the value is observed upon heating the sample at 473 K for 1 h prior to irradiation. A kinetic study of post-recoil thermal annealing of neutron irradiated material is also presented. Effect of pre-heat treatment results in a decrease of rate constants and saturation retention values at respective temperatures while the Eact for the overall process remains almost unaltered.

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Abstract  

Fractional precipitation techniques have been utilized to separate the lower valent and parent forms of56Mn in permanganate targets and an attempt is made to study a few aspects of chemical stabilization of recoil56Mn in permanganates. Ammonium permanganate, recoil behaviour of which has not been studied previously, is chosen as one of the targets along with the potassium permanganate for initial retention and also for isothermal annealing.56Mn initial retentions of about 12% and about 4% are obtained for potassium and ammonium permanganate, respectively, by activation from a Ra–Be neutron source. A usual trend for KMnO4 and the reduction of recoil fragments by ammonium ions in NH4MnO4 are seen through the isothermal annealing study.

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Abstract  

Investigations on isochronal annealing behaviour of /n, / activated56Mn recoils in crystalline potassium and ammonium permanganates have given different results indicating a varying degree of sensitivity of the samples to recoil annealing. The presence of ammonium ion in ammonium permanganate shows the reduction of recoil species during annealing. Vand-Primak model has been utilized to deduce the kinetic behaviour by which the energy of activation is found to be 1.1 and 1.2 eV for KMnO4 and NH4MnO4, respectively. Furthermore, the present work reveals the role of defects in the transient reactions of the lattice stable precursors and hence the mechanism of the recoil reactions.

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