الفهرس 
Introduction and Literature SurveyOnly 14 pages are availabe for public view
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Abstract
The present thesis is mainly concerned towards the development of simple and accurate spectrophotometric method for uranium, thorium and some rare earth elements determination in black sand Egyptian monazite grade 97% from Rosetta area. This monazite contains a lot of impurities with uranium content 0.43%, thorium 5.2% and total rare earths more than 52%. Problems encountering the spectrophotometric technique in rock and minerals analysis are mainly referring to spectral interference. So, to solve these problems solvent extraction was used to preconcentrate the studied elements prior to their determination. N-Methyl-N,N,N-trioctylammonium chloride and Cyanex 921 were used as extractants for the studied elements, followed by spectrophotometric determination of them.
The present thesis was divided into three chapters a brief summary and conclusions which are presented in the following paragraphs.
Chapter I: Introduction and Literature Survey
Include an introduction on the Egyptian black sand deposits and its mineralogical composition. This chapter includes survey on chemical composition and characteristics of the studied Monazite, various methods used for breaking down of monazite such as chlorination of monazite, sulphuric acid breakdown, calcium carbonate/calcium chloride breakdown and sodium carbonate breakdown of monazite. This chapter includes also a survey on uranium, thorium and REEs in Egypt and the methods used for their separation from Egyptian monazite by extraction using different solvents. Also this chapter includes a literature survey on different methods for their determination.
Chapter II: Experimental
Includes the experimental part, the materials, preparation of various stock and standard solutions, instruments used, and different working procedures. Besides, a number of instrumentation methods of analysis that were used for the quantitative determination of the major, minor and trace elements components during the present work as follows:
1) Spectrophotometry for P2O5, SO4, U, Th, REEs, Fe, Ti, Si.
2) Flame photometry for Na and K.
3) Atomic Absorption spectroscopy for (Co, Pb, Ni, Cu, Zn, Cr, V, Mo, Mn and Cd).
The experimental procedure is followed by scanning electron microscope and Infrared absorption spectrometry for monazite and the resulted products to test purity.
Chapter III: Results and Discussion
Includes the results and discussion; several parameters were studied for the optimization of uranium, thorium and REEs extraction using both N-Methyl-N,N,N-trioctylammonium chloride and Cyanex 921.
1- Studied parameters for optimization of uranium and thorium extraction followed by their determination
This part of the work includes the study of several parameters for the best optimization of extraction of uranium and thorium by N-Methyl-N,N,N-trioctylammonium chloride. A combination between spectrophotometric procedure and extraction of U(VI) and Th (IV) ions by this extractant is described.
Firstly, uranium was extracted by 0.5M N-Methyl-N,N,N-trioctylammonium chloride in kerosene at room temperature for 30 minutes at an aqueous to organic phase ratio 1:1 and pH=3. Then U stripping was done by Na2CO3 (2M) at room temperature at an aqueous to organic phase ratio 1:1 for 15 minutes mixing time in one stage. U was then determined spectrophotometrically in the stripped solution by Arsenazo III dye.
After extraction of uranium the raffinate is used for extraction of thorium using 0.75M N-Methyl-N,N,N-trioctylammonium chloride, an A/O ratio of 1:1 for a contact time of 12 min at room temp and pH = 3. Stripping of thorium was done by nitric acid (1M), at room temperature, at an aqueous to organic phase ratio 1:1 and mixing time of 15 minutes. The stripped (Th) was determined spectrophotometrically using Thoron I at λmax= 540 nm with accurate results. The thermodynamic study indicates that the extraction of uranium (VI) and thorium (IV) form monazite in this study is an exothermic process.
2- Studied parameters for optimization of Sm, Pr, and Nd extraction followed by their determination
This section includes also the determination of rare earth elements (Sm, Pr and Nd) after extraction of uranium and thorium by dissolving the mixed rare earth oxide in 55% nitric acid in Pyrex beaker and heating the magnetically stirred mixture to 70°C for 45 minutes , from the REEs leach solution cerium was extracted by TBP in hexane and stripping by 1.5 molar H2O2 in 0.015 molar HNO3. Then, lanthanum extracted by 5% D2EHPA in kerosene, stripping by 1.3 molar HNO3.
The resulted cerium and lanthanum free rare earth raffinate was then subjected to Eu separation by using the combined chemical reduction–precipitation technique. The separation method depends on the reduction of europium by metallic zinc to its bivalent oxidation state followed by selective precipitation of the sparingly soluble europium (II) sulphate. After removing of cerium, lanthanum and europium, the remained REEs solution was subjected to Sm, Pr, and Nd selective extraction and spectrophotometric determination using Cyanex 921 as extractant and chrome azurol S dye. To elucidate the extractability of these elements, different effective parameters were studied. such as contact time, pH value, extractant concentration and organic /aqueous phase ratio. The extraction of Sm(III), Pr(III) and Nd(III) were performed by 1M Cyanex 921, pH value of 3, and phase ratio of 1:1 at a temperature of 25 °C for 15 minutes. These indicate that almost maximal extraction efficiency of three metals was 98% Sm, 99% Pr, and 99.5% Nd. Sm(III), Pr(III) and Nd(III) were stripped from the loaded Cyanex 921 by 1 M HCl, 25 OC at an A/O ratio of 1/1, and shaking time of 10 min. Derivatisation of spectra is the simplest method for increasing the selectivity by overcoming spectral interferences. The fourth-derivative spectra were investigated to eliminate interferences of Sm(III), Pr(III) and Nd(III) in presence of each other after their extraction by Cyanex 921. from the fourth-derivative studies it was found that, there are significant peaks for Sm(III), Pr(III) and Nd(III) at 315, 309 and 318 nm respectively. The optimum parameters were applied for the spectrophotometric determination of Sm(III), Pr(III) and Nd(III) in REEs monazite concentrate using Cyanex 921 as extractant and chrome azurol S dye.