الفهرس 
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Abstract
In this thesis, nano-structured tin oxide SnO2 and nickel oxide NiO have been synthesized by two different methods; sol-gel and sonochemistry approaches. The as-prepared oxides were annealed at different temperatures 250, 500, and 750⁰C to study the effect of thermal treatment on the structural, morphological and the optical properties of these semiconductors. Moreover, these metal oxides have been doped with different metal-ions by employing the sonochemistry route and then, the effect of incorporation of such metal-ions on the structure has also been investigated. Evaluation of the photocatalytic activity for both the pure and doped oxides has been considered by utilizing different techniques like fluorescence probe method and the UV-degradation of organic dye. In addition, the produced oxides were applied for the treatment of real-wastewater samples to determine their efficiency.
This thesis contains three main chapters and the conclusion; the outlines can be summarized as follows:
CHAPTER I: This chapter is divided into two parts; The first part introduces a general introduction about the concept of nanotechnology, the different methods of preparation of nano-structured transition metal oxides, their various applications, the effect of doping these oxides with trace metal ions, and the outstanding properties they exhibit. In addition, one of the current hot topic world wide, wastewater treatment, and the different solutions employed to address this critical problem have also been discussed focusing on the photocatalytic technique, in specific. The second part presents a literature review of recent reports related to the subject of this investigation which display the utilization of metal oxide under study as photocatalysts for the purpose of entire mineralization of dyes resulted from the industrial activities.
CHAPTER II: This chapter demonstrates the different synthetic methods employed to prepare the nanostructured metal oxides and the chemicals used in this study. IT also presents the different characterization techniques employed to explore the obtained structural, morphological, and optical properties of the produced oxides. In addition, the optimized conditions employed during the photocatalytic degradation of the organic pollutants and the models used to investigate the rate constants of reaction were described. Appling the prepared photocatalysts for the treatment of different real samples as case studies under the solar illumination environment has been investigated. Recycling conditions have been taken into consideration for the wide-scale economic point of view.
CHAPTER III: This chapter deals with the obtained data and redisplays them into a simple statement. The different characterization tools, like XRD, FTIR and EDX, show the structural properties of the prepared oxides and ensure the insertion of the doped-elements into the host-crystalline oxide structure. Another technique used is TEM analysis that gives information about the particle size in addition to guarantee the lattice parameters, crystal size values and d-spacing resulted from XRD interpretation. BET studies give an overview about the surface characteristics of the oxides from the pore size and the adsorption/desorption isotherms. Finally, the chapter takes the thesis to the application part, at which the prepared oxides might contribute in solving the world wide problem, wastewater issue, that threatens the human being. The obtained oxide were photocatalyticaly studied through three different techniques, fluorescence probe method, photodegradation of Coomassie Brilliant Blue dye R (CBBR), and solar photocatalytic of real wastewater samples. The photodegradation rate was investigated to determine the relative efficiency of the synthesized pure and doped oxides. Recycling performance of these photocatalysts for several times applying during the industrial wastewater treatment process has been also tested for eight times under solar illumination.
Conclusion
Nanosized pure and doped SnO2 and NiO were successfully synthesized by two different methods namely, sol-gel and sonochemical, and their photocatalytic activity was evaluated throughout the photodegradation process of the Coomassie Brilliant Blue dye.
The obtained results can be summarized as the following:
• XRD analysis of the prepared nano-structured tin oxide SnO2 and nickel oxide NiO confirmed the tetragonal and cubic structure phases with high purity while the average crystallite size ranged from 3-22 nm and 11-40 nm for SnO2 and NiO, respectively.
• Both SnO2 and NiO patterns show remarkable high peak intensities of the samples calcined at temperatures ≥ 500⁰C indicating perfect crystallinity compared to samples calcined at 250⁰C.
• The sonication route has high probability in getting particles in the nanometer regime.
• The corresponding doped sample (Sn0.94Ti0.03Ni0.03O2) show similar XRD patterns without any additional peaks related to dopant atoms/oxides confirming the well insertion of the dopant atoms into the host SnO2 lattice. However, the doped nickel oxide sample (Ni0.94Ti0.03Sn0.03O) displays some extra peaks with weak intensities that may suggest that most of the dopants are well incorporated, and very low concentration of another Ni-based phase formed.
• A slight change upon doping is observed in the lattice parameters, bond length and unit cell volume, which can be attributed to the similarity of the relative ionic radii (octahedral coordinate) of Sn4+(0.69Å), Ti4+(0.60Å) and Ni2+(0.69Å).
• Morphological characterization by HR-TEM showed ultrafine nanoparticles with an average size < 10 nm for the oxides calcined at 250⁰C. The particle size increased upon calcination reaching about 30-40 nm for the samples calcined at 750⁰C.
• According to the increase in the calcination temperature from 250⁰C to 750⁰C, the surface area decreased sharply, from 120 to around 11 m2g-1 and from 75 to 5 m2g-1 for SnO2 and NiO, respectively,
• Diffuse reflectance spectroscopy UV-DR results of the doubly doped tin oxide Sn0.094Ti0.03Ni0.03O2 and nickel oxide Ni0.094Ti0.03Sn0.03O exhibited lower band gap energies 3.24 eV and 3.27 eV, respectively, than that of their corresponding pure oxides.
• Fluorescence probe method recorded rate constants of (11.32 x 10-3 and 12.79 x 10-3) for SnO2 and (18.63 x 10-3 and 26.87 x 10-3) for NiO prepared by Sol-gel and sonochemistry, respectively.
• The oxides, ultra-sonochemicaly prepared, noticeably exhibited higher photodegradation reaction rate 29% and 18% for SnO2 and NiO against Brilliant Blue dye than those prepared by sol-gel method.
• The optical properties and the photocatalytic activity of SnO2 and NiO were remarkably enhanced upon doping which may be regarding to introducing of oxygen vacancies.
• Sn0.094Ti0.03Ni0.03O2 and Ni0.094Ti0.03Sn0.03O2, as novel co-doped materials synthesized by sonochemistry method, are considered to be highly efficient photocatalysts with removal percentage 85% for the Brilliant Blue dye from its aqueous solution.
• The recycling efficiency at the eighth one was estimated to be 70, 70, 68 and 66 % for the SnO2 and NiO prepared by sonochemistry and sol-gel methods, respectively. So, only about 25% was the DROP for the catalyst activity after eight times indicating the possibility of scalable application of the synthesized oxides in industrial wastewater treatment field.