الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 165 |  |  |
| | | from | 165 | | |
Abstract
Summary
This thesis consists of three main chapters:
Chapter (1): Introduction
The first chapter comprises the introduction in which an outline of the definition of nanomaterials, their synthesis techniques and their applications in different fields is presented. This chapter also includes a literature survey on the previous work performed on the simple nanosized oxides along with those performed on the mixed nanosized metal oxides and their nanocomposites. A literature survey also included various applications of metal oxides and their nanocomposites.
Chapter (2): Experimental
This chapter includes a complete description of the materials, reagents and the methods used for the preparation of nanosized TiO2, ZnO and TiO2/ZnO nanocomposites.
(a) Samples preparation
1.Titanium dioxide urchin-like nanoparticles were prepared by hydrothermal method.
2. Zinc oxide urchin-like nanoparticles were prepared by hydrothermal method.
3. (TiO2/ZnO) nanocomposites were prepared by equivalent weight ratios (1:1) for the prepared oxides [ TiO2+ ZnO] were added to 10 mL of double-deionized water. Subsequently, 1% weight of Polyvinyl alcohol (PVA) was added to the solution of the previous mixed oxide suspension. The sonication of mixture was done for 30 min after being stirred for 10 min. The prepared nanocomposite was obtained after drying at 100°C for 2h.
(b) characterization of the as-prepared samples
X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FT-IR), Field emission scanning electron microscope (FE-SEM), Energy Dispersive X-ray (EDX) and UV-Vis spectrophotometer had been utilized to characterize the as-prepared samples.
(c) Photocatalytic studies
Using prepared samples, photocatalytic degradation tests were performed using MB dye as an example of a water pollutant. Included are the results of utilizing several parameters that have an impact on the photocatalytic degradation process.
Chapter (3): Results and Discussion
This chapter contains the obtained results and their discussion. This chapter can be divided into two main sections:
Part 1: characterization of the as-prepared samples TiO2, ZnO and TiO2/ZnO nanocomposites using different instruments such as XRD, FT-IR, EDX and SEM.
Part 2: Photocatalytic studies
In this section, the effects of the variables influencing the removal of the dye from aqueous solutions on nanoparticles TiO2, ZnO, and TiO2/ZnO, respectively, are discussed. When employing nano-oxides of TiO2, ZnO, and TiO2/ZnO as photocatalysts to remove MB.
• The rates of degradation were higher for MB solutions at lower concentrations. After 270 min of irradiation time, the degradation efficiency of 10 ppm over (TZ 350, TZ 550 , T350, T550 and ZnO) reached (95.93%, 88.6%, 84.75%, 76.77% and 64.56%, respectively)
• The degradation performance was directly proportional with loading percent reaching up to 99.87 % dye removal at 0.02 g L-1 within 90 min.
• As the temperature increased over the range of temperatures under consideration, MB photodegradation increased at 300 K.
• The addition of o.o5 g graphene increase photodegradation of MB to be 97.85 % and 99.87% for TiO2/ZnO, TiO2, respectively.
• The fitting kinetic model for MB degradation was found to follow the pseudo first-order model.
• According to the thermodynamic studies, the endothermic nature of the photocatalytic degradation of MB using TiO2, ZnO, and TiO2/ZnO, as well as the negative value of ΔG° proving that photocatalysis is spontaneous process and the positive value of ∆S°, were all proven by the positive values of ΔH° with increasing temperature.
• The MB removal fitted the Langmuir isotherm model for the prepared samples.
• The results showed that the prepared nanomaterials can be reused more than once without significant loss in performance. This means that nanomaterials can provide an efficient and economical method for removing contaminants from water.