الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
In Egypt, low and intermediate level radioactive wastes are produced during research activities of the radiochemical laboratories, research reactors, radioisotope and metallurgical laboratories, activation analysis units, nuclear medicine divisions in hospitals as well as industrial activities. Therefore, concern for the environment and establishment of radiation protection goals have been among the major priorities. Many processes have been developed to curtail radioactive liquid waste and heavy metal pollution, among these methods, solvent impregnated resin (SIR) has increasingly received more attention of it is in recent years because it is simplicity, relatively low-cost, and effective in removing metal ions from wastewaters. The main aim of this work is to test and examine synthetic silica-based ureaformaldehyde (SiO2/UF) composite material which was modified by impregnation using organophosphorus extractant namely Ionquest 801 (2-ethylhexylphosphonic acid mono-2-ethylhexyl ester) for the removal of some hazardous metal ions including; Fe3+ , Nd3+ and Eu3+ ions, from radioactive waste solution. The impregnated SiO2/UF composite material was characterized using some analytical techniques such as thermogravimetric analysis (TGA), infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD) and the structure and morphology of the obtained system were investigated by scanning electron microscopy (SEM) techniques. The efficiency of the impregnated material was investigated using batch sorption technique under different experimental conditions such as, contact time, solution pH, initial metal ion concentration and temperature. Some kinetic models were used such that pseudo-first order, pseudo-second order and intraparticle diffusion models to predict the mechanism of the sorption process. The results illustrated that the mechanism of the sorption process was controlled by pseudo-second order model. The experimental equilibrium data was tested for Langmuir, Freundlich and Dubinin-Radushkviech (D-R) isotherm models in order to determine the best fit isotherm for the sorption process. The results showed that all sorption process were predicted by Langmuir model. The thermodynamic parameters, Gibbs free energy change (∆Go ), enthalpy change (∆Ho ) and entropy change (∆S o ) of the adsorption process were calculated. The negative value of Gibbs free energy change indicates that the adsorption process is spontaneous. The positive value of enthalpy change, confirms the endothermic nature of the sorption process. The positive value of the entropy change shows the increased randomness at the solid/solution interface. A comparison of the sorption capacity of the impregnated composite material with other sorbents reported in the literature was tabulated and indicated that the impregnated composite has much higher sorption capacity than many other sorbents. The whole results indicated that the impregnated SiO2/UF composite can be used as an efficient material for the removal of some lanthanide elements as well as heavy metal ions from aqueous solutions.