الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Ionic substitutions have been introduced as a tool to improve the properties of hydroxyapatites (HAP). Novel nano-sorbents of HAP having different compositions were synthesized by a co-precipitation method and applied in removal of Co(II) and Eu(III) radionuclides from aqueous solutions. The synthesized sorbents were characterized using surface area (BET), FT-IR, X-Ray, TG/DTA, SEM and magnetic properties to clarify their physicochemical properties. The results of characterization confirmed the formation of CNTs / HAP core – shell composites. The role of different parameters on sorption of Co(II) and Eu(III) onto the synthesized sorbents was studied and discussed to clarify the affinity of these sorbents towards Co(II) and Eu(III) and assess the main factors affecting the sorption process. The sorption process is solution pH dependent and ion-exchange is a main mechanism participating in Co(II) and Eu(III) separation beside other mechanisms. Desorption of Co(II) and Eu(III) from loaded samples was studied using different eluents and the maximum recovery is obtained using FeCl3 and HCl solutions. The synthesized sorbents can be regenerated and reused for many cycles. The sorption process follows the pseudo-second-order kinetic model with necessary time of 6 hrs to reach equilibrium. A chemisorption process is expected to be occurred between the studied metal ions and sorbent surface. The sorption of Co(II) and Eu(III) onto the synthesized sorbents is an endothermic process takes place spontaneously. Finally, Co(II) is completely separated from Eu(III) using sorption dynamic study.