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  • Author or Editor: B. Misra x
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Two new methods of constructing a series of partially balanced ternary designs are presented. One from a BIB design and a PBIB design, and the second from a PBIB design alone, obtained by method of differences in both the cases.

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A field study conducted for three years (1992–93 to 1994–95) at the Indian Agricultural Research Institute on a sandy clay loam shows that for sustained production in a rice-wheat cropping system integrated nutrient management involving both organic manures/residues and chemical fertilizers is a must. In control plots receiving no organic manures/residues but as high as 120 kg N ha –1 only 8 t ha –1 yr –1 grain could be produced. This productivity could be achieved by Sesbania/cowpea green manuring or mungbean residue or farmyard manure without any chemical fertilizer; with 80 kg N ha –1 it could be increased to 9 t ha –1 yr –1 . Since the availability of farmyard manure is decreasing due to increased mechanization, the generation of in situ organic residues, preferably a legume, is a better alternative.

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Abstract  

Complexation aided ultrafiltration (CAUF) is an attractive separation process for the removal of trace toxic elements from effluents at low pressures. Freshly prepared polysulfone, polyamide, polyamide hydrazide and polyvinyl butyral blended cellulose acetate membranes are studied with respect to the separation behavior for radioactive cerium tracer in the presence of polyethyleneimine. The effect of polymer loading and pH of the feed system are investigated.

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Abstract  

Batch equilibrium distribution data for Ce3+/H+ and Am3+/H+ systems in 0.2 to 4.0M HNO3 on 1, 2, 4, 8, 10, 12 and 16% crosslinked Dowex 50W resins are reported. These data, along with the mean ionic activity coefficients of the tracer in the mixed electrolyte solutions, were used to calculate the equilibrium constant (K a) uncorrected for the resin phase activity coefficient. The logK a values obtained at various ionic strengths were fit to a second order quadratic equation. Using the fitting parameters, logK a values were calculated for the different resins at zero ionic strength. LogK (equilibrium constant) values were computed by neglecting the changes in the activity coefficient terms in the resin phase due to resin loading. The logK values reported for Ce3+/H+ systems at a few crosslinkages are compared and the magnitude of the error in the approximate calculations is discussed.

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Abstract  

Back-extraction of tri- and tetravalent actinides from diisodecylphosphoric acid (DIDPA) is studied using hydrazine carbonate as back-extractant. In experiments using 0.5M DIDPA–0.1M TBP n-dodecane solution, Am(III), Eu(III), Pu(IV) and Np(IV) are back-extracted, and the distribution ratios are decreased with an increase of hydrazine carbonate concentration. The back-extraction equilibria are confirmed by slope analysis in consideration of neutralization between DIDPA and hydrazine carbonate, which occurs quantitatively during back-extraction. In particular, oxidation of Np(IV) to Np(V) during back-extraction is observed by measuring absorption spectra. The hydrazinium ion acts as an oxidation reagent in the back-extraction of Np(IV). Separation factors of those metals are compared with the results of HDEHP. Hydrazine carbonate back-extracts Np(IV) more selectively from DIDPA than from HDEHP.

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Abstract  

A study on the separation of the long-lived heat generating fission products137Cs and90Sr from acidic solutions has been carried out using a specially fabricated electrodialytic cell equipped with a pair of cation and anion exchange membranes forming a catholyte and anolyte, respectively, and a radioactive feed chamber. The studies were done with feed solutions containing different concentrations of Na+, Cs+ and Sr2+ individually and with a mixture of these cations in 0.3 M HNO3. In all the cases, the transfer of Cs and Sr was found to be greater than 90%. To facilitate the separation of the above radionuclides from higher acidity (∼3.0M HNO3), diffusion dialysis was taken as a possible pretreatment step using a two compartment diffusion cell with an anion exchange membrane in between. All the experiments were done under non-stirring mode.

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