الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Lanthanides and yttrium represent a considerable portion of the fission products obtained from uranium-235 fission in the back end of nuclear fuel cycle. Therefore, it is rather relevant to investigate their extraction chemistry to get more information concerning their behavior towards the novel extractant Cyanex 572. Therefore, the main objective of the work presented in this thesis is directed to study the extraction and separation of Y(III) and Dy(III) from different diluted mineral acid solutions such as HCl, HNO3 and H2SO4 using Cy-572 as a novel extractant diluted in kerosene. The characterization of Cy-572 using different analysis such as potentiometric titration, FT-IR measurements, GC-Mass spectrometry and NMR measurements was studied to identify the ratio of its main components. Within this context two systems are studied based on liquid– liquid extraction and solid–liquid extraction. Recovery of the investigated elements from loaded organic solutions using different stripping agents was carried out.
The thesis is classified into three chapters; namely, introduction, experimental, and results and discussion.
The first chapter, ”Introduction”, includes a brief outline on the nuclear fuel cycle including front end cycle and back end cycle, spent nuclear fuel and the composition of irradiated fuel. Also, the basic aspects of different separation techniques with a special consideration on extraction techniques especially extraction chromatography with column system, extractant and diluents are outlined. In addition, general aspects on the lanthanides are covered including the sources, chemistry, separation feasibility as well as some applications portions of lanthanides on different fields. This chapter is ended by a literature survey related to the present work.
The second chapter, ”Experimental”, contains detailed outline concerning the chemicals employed and their purity. Detailed description for the instrumentation and experimental techniques used during this work are given. Preparation of the working solutions, kieselguhr/Cy-572 and column procedure are reported in details. Methods for determination of lanthanides by arsenazo (III) are also given. In addition, saponification, potentiometric titration experiments are given.
The third chapter, ”Results and discussion”, is classified into two main parts.
The first part liquid-liquid extraction divided into five sections.
In the first section, characterization of Cyanex 572 (Cy-572) as a novel extractant Cy-572 was investigated using potentiometric titration, FT-IR measurements, GC-Mass spectrometry, NMR measurements, diluents effect and saponification effect.
In the second section, the liquid-liquid extraction of Y(III) or Dy(III) from two dilute acids such as HNO3 and HCl were studied using Cy-572 in kerosene under equilibrium conditions. Evaluation of the proposed extraction equilibrium are given and discussed through the effects of different parameters affecting the extraction processes and IR investigation. Further, the recovery of both elements from the loaded organic solutions by different stripping agents as well as regeneration cycles of the loaded extractant was determined.
Based on the slope analysis of the linear relations obtained, distribution ratio (D) vs [H+] and D vs [Cy-572] on log-log scale, IR investigation, the stoichiometry of the extracted metal species was found to be , where, M is related to studied metal ions, Y(III) or Dy(III).
The maximum loading of Cy-572 is 0.122 moles Y(III) per mole extractant after six extraction steps, while the maximum loading of Cy-572 is 0.033 moles Dy(III) in HNO3 acid solutions per mole extractant after five extraction steps. In HCl acid solutions, the maximum loading of Cy-572 is 0.131 moles Y(III) per mole extractant, but the maximum loading of Cy-572 was 0.039 moles Dy(III) per mole extractant.
The increase in temperature in the range (15.0 °C – 65.0 °C) has slight effect on the extraction of Y(III) or Dy(III) from the dilute hydrochloric and nitric acid solutions.
Stripping of Y(III) or Dy(III) were easily performed by 1.0 mol/L HCl solution in one step from both HCl and HNO3 aqueous solutions.
The third section is directed to investigate the extraction of Y(III) or Dy(III) by Cy-572 as extractant in kerosene from aqueous sulfate solutions. The composition of the extracted species was obtained by the slope analysis method and their equilibrium constants were determined.
The maximum loading of Cy-572 is 0.032 moles Y(III) and 0.015 moles Dy(III) per mole extractant in H2SO4 acid solutions.
The mixture of 1.0 mol/L HNO3 and 1.5 mol/L HCl is the best stripping agent for Y(III) and Dy(III) from H2SO4 medium.
The fourth section deals with the separation feasibility of the lanthanides plus Y(III) using 0.075 mol/L Cy-572 from 0.1 mol/L HCl, HNO3 and H2SO4. This section indicated the possibility of efficient separation of heavy lanthanides and Y(III) from light lanthanides as well as individual heavy lanthanides
The fifth section includes fractionation of Monazite leach liquor solution containing different rare earth elements by Cy-572 based on the experimental results obtained in the third section.
The second part is based on solid-liquid extraction investigations of some heavy lanthanide ions such as Dy(III), Ho(III), Er(III), Yb(III) as well as Y(III) from sulfate medium using kieselguhr for chromatography loaded with Cy-572 in both batch and fixed column technique. characterization of the modified kieselguhr was performed using XRF, SEM, IR techniques as well as thermal analysis. Sorption of some heavy lanthanides Dy(III), Ho(III), Er(III), Yb(III) together with yttrium Y(III) from 0.1 mol/L H2SO4 by the prepared kieselguhr/Cy-572 was investigated. The kinetic studies and the isotherm data were described using different models. Thermodynamic parameters and separation feasibility were estimated and discussed. Moreover, chromatographic column breakthrough investigations were performed in a multi element system. Finally, comparison between the present work and the previous reported reviews was discussed.