الفهرس 
General Introduction and Literature ReviewOnly 14 pages are availabe for public view
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Abstract
One of the most promising approaches to revolutionize the environmental remediation techniques especially wastewater treatment is “nanotechnology” which can be defined as a group of emerging technologies that work on nanometer scale to produce materials and systems with fundamentally new properties and functions by controlling the size and the shape of matters.
This thesis aims to study the effect of heteropolyacids on the structural, surface, morphology, optical as well as photoluminescence and photocatalytic properties of TiO2 at different preparation conditions.
The experimental procedures and instrumentation as well as methods of analysis used in this study are presented.
The used experimental techniques are:
- Photochemical reactors
- UV-Visible/diffuse reflectance spectroscopy
- FT-IR spectroscopy
- Chemical oxygen demand (COD) analysis
- X-ray diffraction (XRD)
- Surface area analysis
- Photoluminescence (PL)Spectroscopy
- Transmission electron microscope (TEM) spectroscopy
- Micro analytical tools such as: centrifuge, magnetic stirrer with hot plate and pH Meter……etc.
Moreover, methods used for data treatments and handling are described.
The thesis consists of five chapters:
Chapter 1: Gives a general introduction including photo chemical oxidations technology (nano semiconductor photocatalysis) that play a significant role in cleansing the environment of the waste materials originated from human activities. A theoretical background about the TiO2 as a nano semiconductor photocatalyst is introduced, including (structures, mechanism in photocatalysis, method of preparation, doping with heteropolyacids and evaluating the photocatalytic activity). The literature review concerning the thesis topics is also given.
Chapter 2: Demonstrates different experimental techniques and data analysis methods used in this thesis.
Chapter 3: Includes characterization of heteropolyacids (HPA: PW12 and PMo12) doped TiO2 prepared by sol-gel method under acidic condition in the absence of any template and study the different preparation conditions like different contents of HPA, calcinations temperature and calcinations time on the structural, morphology, optical, photoluminescence and photo-oxidative properties. The optimized HPA / TiO2 sample was applied in real wastewater treatment using UV illumination. The results obtained in this chapter are summarized as follows:
1- The HPA / TiO2 with different contents of HPA (0.0020, 0.0025, 0.0050, 0.0070, 0.0100, 0.0150 and 0.0200 mol) was successfully prepared by sol-gel method in the absence of any template under acidic condition.
2- The prepared nanomaterials were characterized by different experimental techniques and the obtained results are summarized as follows:
a) XRD analysis confirms that all HPA/TiO2 nanomaterials with different contents of HPA prepared by sol-gel method have anatase phase besides rutile phase in some contents of HPA. This indicating that HPA contents plays a vital role in titania phase transformation leading to higher thermal stability specially at high doping concentration. Also, the crystal size decreases with increasing the contents of HPA.
b) The surface area of the HPA/ TiO2 increased as a result of increasing HPA contents.
c) TEM analysis of 0.0050 HPA / TiO2 has aggregated nanospherical-like shape and porous mesostructure.
d) The optical band gap and blue emission bands of HPA/ TiO2 samples showed a remarkable changed relative to pure TiO2. This indicates that the optical properties of prepared HPA/TiO2 are sensitive to the HPA doping.
3- The photocatalytic activity of HPA/TiO2 with different contents of HPA prepared by sol-gel method in the absence of any template under acidic condition is evaluated using fluorescent probe method and dye method.
a) HPA/TiO2 is applied for conversion of Coumarin of non-fluorescent to 7-hydroxycoumarin of fluorescent by production of •OH radical on the surface of semiconductor (fluorescence probe method). The results show that the 0.0050 PW12/TiO2 and 0.0050 PMo12/TiO2 have the good production of hydroxyl radical.
b) HPA/TiO2 was applied for photocatalytic degradation of textile dyes from water under acidic conditions (dye method). Remazol red RB 133 (RR) was selected as examples of textile dyes which already used for dying in many factors. The results show that the 0.0050 PW12/TiO2 and 0.0050 PMo12/TiO2 brought about remarkable improvement in the photocatalytic activity.
4- The decolorization and mineralization efficiency of industrial wastewater sample under UV illumination by highly active nanoparticles 0.0050 PW12/TiO2 reached to 100%, and 50%, respectively, after 8h of illumination.
Chapter 4: Focuses on characterization and photocatalytic activity of PW12 doped TiO2 prepared by capping assisted sol-gel hydrothermal method for real wastewater treatment applications.
The results obtained in this chapter are summarized as follows:
1- The 0.0050 PW12 / TiO2 has successfully prepared by hydrothermal treatment of sol for different times (0.5, 1, 2h). Also, capping assisted sol-gel hydrothermal method used for preparation of 0.0050 PW12 / TiO2 for one hour hydrothermal under acidic conditions.
2- The prepared nanomaterials were characterized by different experimental techniques and the obtained results are summarized as follows:
a) XRD analysis confirms that all nanomaterials prepared by sol-gel hydrothermal or capping assisted sol-gel hydrothermal method have anatase phase. Also, the crystal size values of 0.0050 PW12 / TiO2 increase by increasing hydrothermal time for 1 hour then decreased again. The presence of capping agents effect on crystal size.
b) TEM analysis showed that the hydrothermal time effects on the morphology of 0.0050 PW12 / TiO2 prepared by sol-gel hydrothermal method. Also, the presence of capping agents changes the morphology. CTAB and Triton X-100 have nonporous nanorods as a major phase and small square sheets as minor phase. β-Cyclodextrin has aggregated spherical particles with low mesoporous character. While SDS surfactant leads to formation small porous square sheets.
c) The surface area of the 0.0050 PW12 / TiO2 decreased as a result of increasing hydrothermal time and by using surfactant in preparation method.
d) The optical band gap and blue emission bands of 0.0050 PW12 / TiO2 samples prepared by sol-gel hydrothermal method and capping assisted sol-gel hydrothermal method showed a remarkable changed relative to sample which prepared by sol-gel method. This indicates that the optical properties are sensitive to the preparation method and template assisted preparation method.
3- The photocatalytic activity was evaluated by dye method. 0.0050 PW12 / TiO2 samples prepared by sol-gel hydrothermal methods and capping assisted sol-gel hydrothermal method has the good decolorization of dye than that prepared by sol-gel method. The optimal conditions were achieved for hydrothermal time 1 h and 0.4x10-3 Triton X- 100.
4- The highly active sample (0.0050 PW12/TiO2 prepared by sol-gel hydrothermal method for 1 h and in presence of 0.4x10-3 mol. Triton X-100) successfully mineralized real wastewater samples under sunlight illumination using CPC photoreactor.
5- The obtained results showed that the preparation method and conditions play an important role in modification of the physicochemical properties of HPA/TiO2.