الفهرس | Only 14 pages are availabe for public view |
Abstract Our world extremely suffers from pollution due to urgent need to industry and discharge of factories waste, so most of scientific researches are concerned in solving this crisis. In the last decades, semiconductor-assisted photocatalysis was intensively studied as a ‘green’ method for wastewater treatment. Titanium dioxide (TiO2) is one of the most important photocatalysts due to its non-toxicity, availability, stability and excellent photocatalytic performance. Unfortunately, it has two major disadvantages: its rapid electron-hole recombination rate causing decreasing of its photocatalytic efficiency and its large band gap energy (3.2 eV for pure anatase) causing excluding its activity only under UV irradiation which represents only 2–3% of whole solar-light spectrum. Several techniques are used to overcome these disadvantages such as metal doping, non-metal doping, co-doping and dye sensitization using rose bengal, curcumin, phthalocyanine, porphyrins and metal porphyrins. Porphyrins are intensively colored materials that characterized by their strong absorption in the whole visible range. In the first part of this study, tetra (4-carboxyphenyl) porphyrin (TCPP) was prepared by simple one-pot synthesis to be used as a visible antenna for TiO2 nanoparticles that were prepared via simple template-free sol-gel method. Various loading percentages of TCPP (0.05-1%) were incorporated as photosensitizer on the surface of TiO2 for photocatalytic degradation of Rhodamine B (RB) dye as a primary pollutant model for optimization TCPP%. For TiO2 nanoparticles sensitized with optimum TCPP%, the different parameters affecting the photodegradation of RB dye such as catalyst dose, dye concentration and pH were studied. Also, the effect of scavengers was studied to indicate the nature of reactive species of the catalyst and the mechanism of the photodegradation of RB using TCPP-TiO2 was suggested. In the second part of this study, TiO2 nanoparticles were prepared using template-assisted sol-gel method using various templates such as Tween 80 (T80), Octaldecylamine (ODA), Cetyltrimethylammonium bromide (CTAB) and polyvinylpyrrolidone (PVP). Among these templates, T80- templated TiO2 nanoparticles were the most reactive sample toward the photodegradation of RB. Then, different concentrations of T80/isopropanol solutions (0-50%) were utilized in a modified template-assisted sol-gel method. The concentration of T80 (T80%) was found to affect the whole physical properties such as crystalline parameters, optical properties, micromorphology, nanomorphology, surface area and photocatalytic activities of Tween 80 templated TiO2 nanoparticles. Finally, TCPP was anchored on the surface of T80-TiO2 nanoparticles to act as a visible antenna to enhance its photocatalytic activity toward the visible light region. The skeleton of the thesis is divided into four main chapters: Chapter 1: Introduction This chapter explore the crisis of water pollution and its severe effect on the human health. Also, this chapter explore the traditional and advanced methods of waste water treatment. At the end of this chapter, a recent literature survey at the scope of the thesis was presented. Chapter 2: Experimental This chapter presents a detailed description of the materials, equipment and the various experimental techniques used in the preparation, characterization and application of the prepared catalysts. Chapter 3: Results and discussion This chapter contains the detailed interpretation of all the experimental results of physicochemical characterization of the prepared materials and their application in the photodegradation process Chapter 4: Conclusion and future trends This chapter summarize the main conclusion of the experimental work and explore our future scope and trends. Appendix 1: Kinetic data This appendix contains all the detailed kinetic tables and graphs of the photodegradation experiments that performed during the experimental work of the thesis. Appendix 2: Published articles This appendix contains the print form of the published paper ” Effect of porphyrin on photocatalytic activity of TiO2 nanoparticles toward Rhodamine B photodegradation” at the Journal of Photochemistry & Photobiology, B: Biology 176 (2017) 25–35. |