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  • Author or Editor: S. Srivastava x
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Abstract  

The sorption of some monovalent, divalent and trivalent metal ions has been studied on a mixed and doped hydrous oxide of iron and zirconium (with iron as a major constituent). The sorption of Sr2+, Cr3+ and Cd2+ was found to be exceptionally high, besides this, the mixed oxide also exhibits significant uptake of Rb+ and Cs+ ions. The effect of doping is quite interesting as the uptake of Fe3+ increases 2-increases 2-fold when the mixed oxide is doped with Sn(II) ion. An enhancement of the same magnitude is also observed in the case of La3+ ions. The amount of maximum uptake was determined and found to be linearly related to the ionic potentials, i.e. charge to radius ratios of the entering cations.

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Abstract  

The effect of various temperature treatments on TL response characteristics of CaSO4: Dy has been investigated for its reusability when the phosphor has been previously irradiated to increasingly higher gamma doses. In practice, annealing at a standard temperature, namely 400 °C, usually precedes the use or reuse of the phosphor. However, the study demonstrates that the phosphor with a previous history of high accumulated doses does not completely retain its original TL response characteristics with 400 °C treatment unless the phosphor is treated at an elevated temperature, namely 650 °C.

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Abstract  

A mixed hydrous Fe(III)–Zr(IV) exhibits enhanced adsorption of anions in comparison to its constituent oxides. The uptake has been observed at pH 2.0, as a function of initial salt concentration and the product shows specific affinity for Cl, SO 4 2– and PO 4 3– ions. Doping the mixed oxide with Sn(II) improves its sorption capability for halide ions, while no significant enhancement is observed in the case of polyvalent anions.

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Abstract

A number of samples of sodium and silver phosphate glasses doped with various compositions of some transition metals viz. iron, manganese and zinc chlorides alongwith undoped samples of sodium and silver phosphate glasses were synthesized and characterized by X-ray diffraction, IR spectral, electrical conductivity and differential scanning calorimetry (DSC). The glass transition temperature (T g) and crystallization temperature (T c) values obtained from DSC curves were found to increase with increasing concentration of the dopant Fe/Mn/Zn chlorides in both sodium and silver phosphate glasses and the following sequence is observed:

T g(–FeCl3)>T g(–MnCl2)>T g(–ZnCl2)

T c(–FeCl3)>T c(–MnCl2)>T c(–ZnCl2)

The increase in T g and T c values indicate enhanced chemical durability of the doped glasses. The electrical conductivity values and the results of FTIR spectral studies have been correlated with the structural changes in the glass matrix by the addition of different transition metal cations as dopants.

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Abstract  

The extraction behaviour is reported of zinc(II), cadmium(II) and mercury(II) complexes of thiocarbohydrazide in benzene, chloroform, carbon tetrachloride, di-isopropyl ether, ethyl acetate, amyl acetate, and amyl alcohol. The separation of the three elements has been achieved by the use of various masking agents, as well as by making use of the effect ofpH on their extractability.

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Abstract  

A short-term greenhouse pot culture study was carried out to study the agronomy efficacy of P sources for cotton crop in a vertisol. The sources of P were single super phosphate (SSP), diammonium phosphate (DAP) and nitrophosphate tagged with 32P and applied at three rates (30, 60 and 90 kg P2O5 ha−1). The results indicated that the dry matter yield (DMY) of cotton shoot, P uptake, percent P derived from fertilizer (%Pdff) and Avalue of the soil increased significantly with increasing fertilizer rate, whereas the percent fertilizer P utilization (%FUP) was found to be higher at lower fertilizer rates. Among the fertilizer sources SSP was found to be superior in enhancing DMY of cotton, P uptake and %FUP as compared to other fertilizers. %Pdff was found to be at par in SSP and DAP treatments and was significantly higher in comparison to NP and reverse was true in case of A-value of the soil. Results on equivalent ratio showed that SSP and DAP are equally efficient, whereas, 1 kg P as SSP was equivalent to 7.47 kg P as NP. In general, efficacy of phosphatic fertilizers for cotton crop in vertisol was found to be in order of SSP>DAP>NP.

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Abstract  

Using the pulse radiolysis competition kinetic technique, OH radical rate constants with 12 metal DTPA complexes were determined in neutral aerated aqueous solutions. They are in the range of /1.3–5.9/×109 dm3 mol–1s–1. To a first approximation, the rate constant was found to decrease linearly with an increase in the field strength of the metal ion (q/r2).

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