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Abstract  

The suitability of silica gel for the concentration of small quantities of palladium (20 μg in 500 ml) and zinc (5 μg in 500 ml) by a quick and simple method has been demonstrated. It has been found that the metals are taken up completely from their dilute solutions by silica gel, but the quantity of silica gel has to be increased with increasing volume of the solution containing the trace metals. Complete elution (desorption) of the deposited ions has been carried out with a dilute hydrochloric acid solutiion. The eluted palladium and zinc have been determined spectrophotometrically and radiometrically, respectively.

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Abstract  

A rapid procedure is described for the separation and determination of 0.025 mg to 1.0 mg quantities of As(V), V(V), Mo(VI) and W(VI) from small quantities of Cu(II), Ni(II), and Zn(II) using silica gel as the selective sorbent for the cations. The individual anionic components, which remain in the supernatant solution after separation from the cations, are determined by colorimetric methods. The complete recovery of As(V) in supernatant solution has also been tested radiometrically using76As as the radioactive indicator. The sorbed cations after extraction with dilute hydrochloric acid are determined by EDTA titrations.

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Abstract  

Extraction of zinc(II) and cadmium(II) from ammonium thiocyanate solutions has been studied in benzene in the presence of pyridine. The effect of such variables as the pH of aqueous phase and concentration of metal, thiocyanate and pyridine on extraction has been investigated and the extracting species identified. Extraction behaviour of silver(I), manganese(II), cobalt(II), mercury(II) and thallium(III) has also been studied under identical conditions and some binary metal ion separations of analytical and radiochemical importance are reported.

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Germinated brown rice received great attention as healthy ingredient and can be used as an alternative source in the malting and brewing industry. The germination capacity, physico-nutritional properties, sugars, and diastase enzyme activity of brown rice affected by germination times and temperature were determined and compared with control. Soaking in water increased the moisture content of brown rice. Germination rate of brown rice was also increased by higher germination time and temperature and reached maximum after 48 h of germination at 35 ºC. However, dry matter loss, grain weight, and density are affected to a lesser extent. Germination significantly (P<0.05) affects the crude protein, fat, fibre, and ash contents. Total carbohydrates content showed linear relationship with germination time and temperature. During germination, hydrolytic enzymes act on starch, reducing its concentration and resulting in higher total and reducing sugars amounts. Increase in germination time and temperature also increased diastase enzyme activity.

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Abstract  

A number of samples of sodium phosphate glasses doped with Cd/Co or Ag chlorides were prepared and characterized by X-ray diffraction, IR spectral, ion transport and DSC studies. It was found from DSC studies that the glass transition temperature (T g) and crystallization temperature (T c) values increased with the increasing concentrations of the dopants Cd or Co chlorides. However, the T g and T c values were found to decrease when the AgCl was taken as the dopant and the following sequence is observed: T g(CoCl2)>T g(CdCl2)>T g(AgCl); T c(CoCl2)>T c(CdCl2)>T c(AgCl) These results have been discussed and explained on the basis of changes in the structure of sodium phosphate glassy matrix by the addition of different cations as dopants.

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Abstract  

The present work deals with study of uptake behavior of zinc and mercury ions by hydrous ceric oxide applying a radiotracer technique. The influence of various parameters such as concentration, temperature and pH have been examined. It was observed that the amount of zinc and mercury ions adsorbed at equilibrium increases with increase of adsorptive concentration (1.0·10−7 to 1.0·10−2M), temperature (303–333K) and pH (ca. 3–10). Concentration dependence data agree well with the classical Freundlich isotherm. The radiation stability of hydrous ceric oxide was also investigated by exposing it to a 11.1 GBq (Ra−Be) source associated with γ-dose of 1.72 Gy·h−1 and also using a60Co source (4.66 kGy·h−1). Adsorption of these metal ions in the presence of some monovalent and divalent cations and complexing agents has also been included in the study.

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Inorganic particulates in removal of toxic heavy metal ions

VIII. Removal of zinc, cadmium and mercury ions from aqueous solution by hydrous titanium oxide

Journal of Radioanalytical and Nuclear Chemistry
Authors:
S. Mishra
and
V. Singh

Abstract  

Adsorption behavior of zinc, cadmium and mercury ions on hydrous titanium oxide in aqueous solution has been studied as a function of concentration of the metal ion (10−2−10−7M), temperature (303–333 K) and pH 3–10 by applying radiotracer technique. The kinetics of adsorption follows the first order rate law and agrees well with the classical Freundlich isotherm. The removal was found to increase with increasing pH but was suppressed in the presence of EDTA. The overall process is endothermic and irreversible in nature.

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