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  • Author or Editor: M. Attallah x
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Abstract  

Application study for the evaluation of sorption characteristics of sawdust as an economical sorbent material used for decontamination of radioisotopes cesium and europium from aqueous solution has been carried out in the present work. In this respect, sawdust (untreated and treated by HNO3) has been prepared from the commercial processing of wood for furniture production. Pore properties of the activated carbon such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by N2 adsorption and DFT software. Radiotracer method onto sawdust from aqueous solutions was studied in a batch technique with respect to pH, contact time, temperature. The kinetics of adsorption of Eu3+ and Cs+ have been discussed using five kinetic models namely, pseudo-first-order model, pseudo-second-order model, Elovich equation, intraparticle diffusion model, and modified Freundlich equation that have been tested in order to analysis the experimental data. Kinetic parameters and correlation coefficients were determined. It was shown that the second-order kinetic equation could describe the sorption kinetics for two metal ions. The metal uptake process was found to be controlled by intraparticle diffusion. Thermodynamic parameters, such as ΔH, ΔG and ΔS, have been calculated by using the thermodynamic equilibrium coefficient obtained at different temperatures. The obtained results indicated that endothermic nature of sorption process for both 152+154Eu and 134Cs onto sawdust.

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Abstract  

This paper adresses the development of a new radiopharmaceutical for cancer imaging and therapy. The optimization of the labeling of thymidine analogous, cytarabine, with 125I is described. High radiochemical yield and purity 98% was obtained by reacting 50 mg cytarabine with 125I in the presence of iodogen as oxidizing agent and 0.5M phosphate buffer of pH 7 at 65 °C for 30 minutes. Preliminary in-vivo study was done in non-tumor bearing mice. The results revealed that this new tracer, 125I-cytarabine, has a high affinity to be localized in tissues of high proliferation rate, e.g., bone marrow 10%, 60-minute post administration. Also, the labeled compound was cleared quickly from most of the body organs and concentrated in bladder 55%, 60-minute post administration. These findings suggest that 125I-cytarabine, allows imaging and treatment of cancer. 125I-cytarabine meets most of the requirements to be used as a successful diagnostic and therapeutic agent: it is a low molecular weight molecule that diffuses readily in tissues, it will not induce an antibody response, thereby leading itself to repeated injection or continuous infusion.

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Abstract  

Phosphogypsum (PG) is a residue of the phosphate fertilizer industry that has relatively high concentrations of harmful radioactive materials. The reduction in concentration of the radionuclides from PG was investigated. The removal process is based on leaching of radionuclides using suitable organic extractants. The studied radionuclides were 226Ra, 210Pb, 238U and 40K. The factors affect the leaching process such as type of leaching materials, contact time, concentration of the desired solvent, liquid to solid ratio, and temperature were studied. Based on the experimental results, about 71.1, 76.4, 62.4, and 75.7% of 226Ra, 210Pb, 238U and 40K respectively were successfully removed from the PG. The reduction in the concentration of radionuclides was accompanied by reduction in the concentration of rare earth elements (∑REE) equals to 69.8%. Using the desired organic extractant under optimum conditions for treatment of the PG waste leads to obtain a decontaminated product that can be safely used in many industrial applications.

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