الفهرس 
1.1.1. Sources of Radioactive WastesOnly 14 pages are availabe for public view
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Abstract
The increasing concern towards the protection of environment and optimization of a wide range of industrial processes and activities in both nuclear and non-nuclear fields imposes the need for the developing an advanced processes for treatment of liquid wastes. The work presented in this thesis will address the above objective with respect to the removal of persistent organic pollutants from aqueous solutions. The experimental work carried out in the present thesis is based on preparation, characterization and applications of Ti-based LDH as integrated photocatalysts. Chapter 1: Introduction This chapter includes an introduction about the radioactive wastes, its sources and classifications. It also includes a review on the methods of treatment of radioactive wastes. There is a review on some advanced oxidation processes (AOPs) especially heterogeneous photocatalysis. Finally, this chapter includes a review on layered double hydroxide, occurrence, chemical composition, synthesis and application. Chapter 2: Experimental This chapter includes the experimental part of this work; first part of this chapter involves the used chemicals, their purity grade and sources. The second part of this chapter includes the methods of preparation of Ti-based LDH. The last part of this chapter includes the used equipment, instruments, measurements and photocatalytic reactor. Chapter 3: Results and discussion This chapter contains the experimental results obtained in this work, and divided into three main parts as follows: 3.1. Structural characterization The prepared photocatalysts were characterized using different techniques. 3.1.1. X-ray diffraction The X-ray powder diffraction patterns of the synthesized materials are presented. These results clarify that the produced particles are pure Mg/Al LDH with octahedral structure. The composite CSPC, that composed from LDH supported on TiO2, show diffraction lines of both LDH and TiO2 implying the presence of admixture of anatase and Mg/Al LDH. 3.1.2. FTIR Analysis The FT-IR spectra of the prepared samples are recorded .The spectra of the unmodified samples are similar and composed of three vibrations. The broad absorption bands revealed in 3600-3300 cm-1 region could be assigned to the symmetric and asymmetric stretching of hydrogen bonded water molecules. The presence of coordinate water molecules existing in the interlayer structure was sensed around 1460 cm-1due to δ(HOH) bending vibration. The band arising at 1375 cm-1 should be ascribed to ν(NO3) stretching frequency of –NO3 inter layer anions in LDH. Also, two characteristic peaks for bending vibration of –NO3 in the inner layer skeleton were observed at 1740 and 824 cm-1. preparations of various organo-catalysts by anion exchange between –NO3 inter layer anions and the anionic surfactant SDS, led to the appearance of new peaks and disappear of others. The new peaks detected at ~ 2833-2933 cm-1 may be ascribed to the stretching vibration of –CH2. Also, the band revealed at 1056 and 1226 cm-1 could be assigned to asymmetric and symmetric vibration of S=O. The vanish of the peak corresponding to ν(NO3) vibration and that observed at 1375 cm-1 elucidate the replacement of inter lamellar -NO3 anion with SDS anion. 3.2. Surface morphology. 3.2.1. Scanning electron microscope (SEM) analysis The morphology of the prepared photocatalysts is depicted. The scanning electron microscope observation revealed that, the surface morphology of the parent (unmodified) photocatalysts has plate-like agglomeration of hydrotalcite particles. Close inspection to SEM pictures clarifies that the surfaces of prepared photocatalysts are highly rough surface. The SEM of TiLPC shows the surface morphology of the photocatalyst in which Ti cations were exchanged with the metal ions of LDH by iso-amorphous substitution. The incorporation of Ti at the surface of LDH made slightly change at the surface of photocatalyst. These features were obviously changed in MLPC due to the incorporation of Ti in the lattice structure of the phoocatalyst. These characteristic are consisted with that revealed from XRD analysis. 3.2.2. Transmitting electron microscope and EDX spectrum The transmitting electron microscope (TEM) images of the synthesized photocatalysts are presented. The transmitting electron microscope (TEM) clarifies that, a plate-like shaped agglomerates have an octahedral structure. The successful preparation of TiO2 and LDH in a core-shell structure was confirmed by the picture given. The picture reveals a dark centered core of TiO2 covered by a homogenous pale shell of LDH. The particles, in general, have homogenous spherical shapes. The features depicted for TiLPC sample is similar to LDH sample. On other hand, the incorporation of Ti in the lattice structure of MLPC, clearly changed the TEM feature of this photocatalyst. These results are in a good agreement with that previous detected from XRD and SEM analysis. The EDX patterns of the synthesized materials are illustrated. The EDX plot of LDH shows peaks indicative to the presence of Mg, Al and Ti elements. a 4. Band gaps The light absorption by a material and the migration of light-induced electrons and holes are the most key factors controlling the photocatalytic activity of this material. This property is relevant to the electronic structure characteristics of the material. The band gap of the synthesized photocatalysts was determined by plotting the relation of (αhʋ)2 vs hʋ. The photocatalytic activity of the prepared composites was evaluated by studying the degradative removal of phenol, EDTA and TTA under different experimental conditions. The preliminary experiments documented that the applied photoctalysts shows a potential removal of these organic ingredient and are easily separated from the reaction solution. 5.1. Effect of pH The solution pH value plays an important role in photocatalytic degradation of various pollutants. The influence of pH value on the catalytic efficiency of the prepared materials was studied by applying various initial pH values ranged from (4 – 9). 5.2. Effect of mass ratio The role of mass ratio on the photodegradation of phenol was studied by preparing various mixtures have different mass ratios of titanium dioxide (as a photo-sensitive surface) and layered double hydroxide (as a highly hydroxilated surface). The participation extent of TiO2 and LDH and the synchronization between them was also verified. For this purpose, various weights of LDH were mixed with a fixed amount TiO2 to obtain mixtures of LDH: TiO2 have the ratios 1:1, 1.5:1 and 2:1. These mixtures were used in studying the degradation of phenol in aqueous solution, and the obtained data are represented. 5.3. Surfactant concentration Intercalation of linear alkyl anions in the MgAl–LDHs was done through ion-exchange reactions. Specifically, sodium dodocyl sulphate (SDS) was exchanged with the NO3- anions in the MgAl–NO3 LDH. The effect of SDS concentration was carried out on MPPC (LDH) using various concentrations of SDS ranged from 1x10-2 to 5x10-4 M, and the revealed data are given. In the modified photocatalysts, the variation of SDS concentration did not affect the removal of phenol. 6. Phenol removal 6.1. Original prepared photocatalysts The photocatalytic degradation of phenol using differently prepared photocatalysts was carried out in using Uv-irradiated reactor. The synchronization between the highly hydroxlated surface LDHs and TiO2 was effectively degrade phenol in aqueous solution. 6.2. Modified photocatalysts The photocatalytic degradation of phenol over the modified catalysts was carried out. The action of sodium dodocyl sulphate anion intercalation was to change catalyst nature from hydrophilic to hydrophobic nature, as well as, increasing the surface area of the catalyst. 6.3. Reformed photocatalyst he calcinations of i at c for hrs lead to the formation of mixed oxide of Mg, Al and Ti. After reformation of TiLPC oxides, the photocatalytic degradation of phenol over the reformed catalyst (RTiLPC) was decreased. This might due to the Ti at the surface of TiLPC dissolute into matrices lattice after reformation which affects the removal efficiency. 7. Ethylene diamine tetra acetic acid (EDTA) removal The degradation of EDTA in an aqueous solution has initial concentration of 1000 mg/L was carried out using the prepared photocatalyst and the obtained data are illustrated. 8. Thenoyl trifluoro acetonate (TTA) removal The degradation of TTA with an initial concentration 100 mg/l was carried out using all prepared photocatalysts, in UV irradiated reactor and the results are presented. 9. Spent catalyst The spent photocatalysts resulted from the photodegradation process were subjected to further characterization to investigate the stability and the possibility of regeneration of photocatalysts.