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  • Author or Editor: R. Qadeer x
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Summary  

A commercial activated charcoal has been tested as an adsorbent for the removal of neodymium ions from aqueous solutions. The adsorption behavior of neodymium ions on activated charcoal from aqueous solutions has been studied as a function of shaking time, neodymium ions concentration and concentration of different acids. Results reveal that the adsorption equilibrium is attained within 30 minutes, and diffusion of neodymium ions into the pores of activated charcoal controls the adsorption process. The adsorption process follows the first order kinetics. The Langmuir isotherm equation was obeyed well in the whole range of concentration studied. The influence of different cations and anions on the adsorption of neodymium ion from aqueous solutions have also been investigated. Approximately 98% of neodymium ions adsorbed onto activated charcoal could be recovered with 40 ml of 3M HNO3 solutions.

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Abstract  

The thermo non-oxidative degradation of PVC and the effects of alkaline earth metal (Be, Mg, Ca, Ba) stearates were studied by thermogravimetry in the temperature range 150 to 500°C. The alkaline earth metal stearates were observed effectively reduce the dehydrochlorination of PVC. The synergistic effects of combinations of these salts with lead stearate were also studied and are discussed. Kinetic parameters such as the activation energy, order of reaction and Arrhenius factor were calculated by the Coats and Horowitz methods. The results showed that these metal stearates increase the activation energy required for the dehydrochlorination of PVC.

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Abstract  

A simple X-ray fluorescence (XRF) spectrometric method for the determination of Cd, Hf, Hg, and Gd in uranium solution has been developed, where sample solutions were introduced to the XRF spectrometer directly in simple polyethylene bottles. The matrix effects have been rectified using standards of similar composition. Statistical evaluation has established it as a fast and reliable method applicable to trace analysis.

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Abstract  

The adsorption of thorium(IV) ions on molecular sieve (13X type) powder from aqueous solutions has been studied as a function of shaking time pH, thorium ion concentration and temperature. The conditions of maximum adsorption of thorium ions obeys Langmuir and D-R isotherms over the entire concentration range studied. Thermodynamic quantities such as H, G and S have been calculated fromK D values determined at various temperatures. The results show endothermic heat of adsorption, but negative free energy value indicates that the process of thorium adsorption on molecular sieve powder is favored at high temperature. The influence of various cations and anions on thorium(IV) ion adsorption was examined. A wavelength dispersive X-ray fluorescence spectrometer was used for measuring the thorium ion concentration in solutions.

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Abstract  

Estimation of strontium has been studied by wavelength dispersive X-ray fluorescence spectrometery (WDXRF) as an analytical technique using Sr K as an analytical line. Lower limits of detection, precision, and intensities were plotted against counting time and concentrations to assess optimum time for measurement, expected scatter of the results, and calibration curves for intensity to concentration relationship. For its assessment the best equations determined by regression and least squares fitting along with a standard multiple addition technique were applied to a complex fuel admixture and simulated nuclear fuel solutions at a bum up of 650 GJ/Kg after a 0.5-year cooling time.

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Abstract  

Adsoprtion of gadolinium on activated charcoal has been studied as a function of shaking time, pH, concentration of adsorbate and temperature. Gadolinium adsorption obeys the Langmuir isotherm. Ho and So were calculated from the slope and intercept of the In KD 1/T plot. The influence of different cations and anions on gadolinium adsorption has been examined. The adsorption of other metal ions on activated charcoal has been studied under optimum conditions to check the selectivity of gadolinium adsorption. Consequently, gadolinium was removed from Ni, V, Zn, Cu, Rb, Sr and Mn. More than 97% of the adsorbed gadolinium on activated charcoal can be recovered with 35 ml of 3M HNO3 solution. Wavelength dispersive X-ray fluorescence spectrometer was used for measuring gadolinium concentration.

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Abstract  

The adsorption of cerium on activated charcoal has been studied as a function of shaking time, pH, concentration of adsorbate and temperature. The adsorption of cerium obeys Freyndlich and Langmuir isotherms. The influence of different cations and anions on cerium adsorption has been exmined. The adsorption of other metal ions on activated charcoal has been studied under specified conditions to check its selectivity for cerium adsorption. Consequently, cerium was removed from a mixture containing Ce, Ba, Sr, Ru, Cs, Cr, Nd, Pr and In. About 99% of the adsorbed cerium on activated charcoal can be recovered with 3M HNO3 solution. A wavelelngth dispersive X-ray fluorescence spectrometer was used for measuring the cerium concentration.

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Abstract  

Effects of alkali metals, alkaline earth metals and some lanthanides on the adsorption of uranium on activated charcoal from aqueous solutions have been studied. These effects are correlated with the ionic radii of metal ions present in the solutions. Adsorption capacity, Xm and binding energy contant, K for uranium adsorption were calculated from the Langmuir equätion. The mean energy of adsorption, Es was calculated from adsorption energy constant, K, values determined from the Dubinin-Radushkevich isotherm equation. Wavelength dispersive X-ray fluorescence spectrometry was used for measuring the uranium concentration.

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Summary  

The adsorption of strontium ions from aqueous solution on a Pakistani coal powder has been studied as a function of shaking time, amount of adsorbent, pH, and strontium ion concentration. Conditions for the maximum adsorption of strontium ions have been established. Results reveal that the diffusion of strontium ions into the pores of coal powder occurs during the adsorption process and intra-particle diffusion controls the kinetics of the process. The Langmuir and D-R adsorption equations are valid over the entire range of studied concentration. The influence of different anions on the adsorption of strontium ions was also studied.

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