الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Samples of zirconium titanium phosphate (ZTP) inorganic ion exchangers were locally synthesized, with different Zr: Ti mole ratios 95:5, 75:25, 25:75 and 5:95, as well as ceric tungstate (CeW). The samples were characterized using FT-IR, X-ray-diffraction (XRD), scanning electron microscopy (SEM) and pore sizer. The adsorption behavior of lanthanide elements, Ce(III), Tb(III) and Yb(III) traced by their corresponding radioactive isotopes 141Ce(III), 160Tb(III) and 169Yb(III) was studied under static conditions. The influence of some parameter: such as V/m (mL.g-1), solution pH, contact time, particle size, metal ion concentration and temperature on the adsorption kinetics were intensively studied in this work. The obtained data have shown that the adsorption is controlled by particle diffusion in each case. The calculated diffusion coefficients of all studied lanthanide ions have values in the range of 10-14 m2.s-1 which indicated that the sorption has a chemisorption nature. The percentage uptake values have generally the sequences Tb˃Yb˃ Ce. This result may suggest the adsorption of Yb as partially hydrated ions in contrast to Tb and Ce where dehydrated ions are adsorbed in the case of Tb(III) and Ce(III). Thermodynamic parameters such as changes in Gibbs free energy (ΔG◦), enthalpy (ΔH◦) and entropy (ΔS◦) were calculated. The isotherms and kinetics of the adsorption process were analyzed using different models. The adsorption was found to follow Langmuir isotherm better than Freundlich and that the pseudo-second order kinetic fits the adsorption data. Samples of Egyptian monazite and phosphate ores obtained from black sand of Abou- Khashaba, Rashied (Rosetta) area on the Mediterranean Sea coast and Om Salma mine at El-Sibaiya mine Nile valley at Lat 25° 18/ 16// & Long
33° 5/ 31//, respectively, were analyzed for some lanthanides and accompanying
elements using instrumental neutron activation analysis (INAA). The analyses
were carried out qualitatively and quantitatively, under various conditions of
selective cooling and counting time. The use of a high resolution HPGe detector
connected to a PC based MCA enabled good accurate simultaneous multi -
element non- destructive analysis in a single irradiation run.
The analyzed elements in monazite ore samples were Ce, Nd, Eu, Gd, Tb,
Yb and Sc, La and the accompanying elements were the following: Co, Cr, Fe,
Hf, Nb, Zn, Zr in addition to the actinides Th and U, whereas after, relatively
longer cooling time the following lanthanide elements were analyzed Ce, Nd,
Eu, Gd, Tb,Yb and Sc, beside the accompanying elements; Co, Cr, Fe, Hf, Nb,
Zn, Zr and Th.
The analyzed elements in El-Sibaiya phosphate ore sample , after
relatively short cooling time were: the lanthanides: La, Ce, Eu, Lu, Nd, Sm, Gd,
Tb and Yb, in addition to the accompanying elements: As, Ba, Br, Ca, Co, Cr,
Fe, Hf,Na, Rb, Sb, Sc, Se, Sr, the actinide Th, U, Zn and Zr . Whereas after,
relatively longer cooling time the following elements were analyzed: Ce, Nd,
Eu, Gd, Tb and Yb beside the accompanying elements; Cr, Fe, Hf, Nb, Sc, Th,
Co, Zn and Zr.Two certified reference materials (CRM) were used in this study,
these were: IAEA soil- 7 and Estuarine sediment IAEA – 405.
In addition to that determination of U and Th contents in the analyzed
samples was also carried out by measuring and comparing the natural
radioactivity of definite radioactive daughter isotopes in the natural decay series
of 238U, 235U and 232Th in standards and samples.
Radioactive isotopes 141Ce, 160Tb, 169Yb, 95Zr, 181Hf and 95Nb were
prepared by neutron irradiation to trace the corresponding elements for studyingtheir adsorption under certain conditions to study the effect of some parameters
on the adsorption.
Radiochemical separation studies for the analyzed elements in solutions of
the irradiated monazite and phosphate ore samples in different acids were
carried out. Ion exchange technique was applied under static and dynamic
conditions.
The organic cation and anion exchangers, Dowex-50X8 and Dowex -1X8,
respectively were also used to assure the type of the proposed ionic species
present in solutions or adsorbed on the synthesized inorganic ion exchangers.
Different factors affecting the adsorption were studied. Good group separation
of the analyzed lanthanide elements from the accompanying elements was
achieved. In addition separation of the very important actinides Th, Pa, U and
Np from other elements was achieved under certain conditions.
Keywords: Adsorption, Separation, lanthanides, Instrumental neutron
activation analysis, Monazite ore sample, Phosphate ore sample, Inorganic ion
exchangers (zirconium titanium phosphate and ceric tungstate), Organic
exchangers, Uranium, Thorium.