Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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COAR Access Rights: search.filters.coarAccessRights.open accessSubject: search.filters.subject.Titanium dioxide

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Now showing 1 - 5 of 5
  • Master Thesis
    Production and Characterization of Emulsion Derived Porous Sioc+tio2 Submicron/Nanospheres
    (Izmir Institute of Technology, 2020) İçin, Öykü; Ahmetoğlu, Çekdar Vakıf
    The water resources are polluted because of the widespread use of dyes in the industry, resulting in a major ecological threat. Among the various water treatment techniques, adsorption and photocatalytic degradation methods are the most preferred owing to their easy applicability, low cost, and high efficiency. Silicon oxycarbide (SiOC), which is a type of polymer-derived ceramic, has the potential to be used in harsh environmental conditions thanks to its strong chemical stability and oxidation resistance, that being said it can also be used as a photocatalyst substrate. Titanium dioxide (TiO2) photocatalysts are extensively used for purification of contaminated waters. And also, TiO2 particles are synthesized with various material groups to investigate the adsorption and photocatalytic effect. In this thesis, initially, submicron/nano SiOC spheres were produced via an oil in water (o/w) emulsion technique by using parameters such as two types of preceramic polymer precursors (silicon oil and resin), mixing types (magnetically and ultrasonically), and different pyrolysis temperature (600-1200 oC). Upon the formation of submicron/nano SiOC spheres, selected samples were impregnated with a different molar of titanium oxide precursor solution (Titanium(IV) n-butoxide (TBT)) and calcined at 450 °C for 4 h. Various amounts of (0-5-10-20 wt.%) TiO2 containing submicron/nano SiOC spheres were produced and then characterized in depth by various techniques. Finally, the effects of pyrolysis temperatures and the amount of TiO2 were investigated in terms of adsorption and photocatalytic performance against aqueous cationic dye (methylene blue) (MB) solution. In the adsorption experiments, pure SiOC submicron/nanospheres (UM1200), pyrolyzed at 1200 oC, showed the best performance at the end of 24 h in the dark with 64% adsorption. In photocatalytic experiments, samples obtained by coating the SiOC substrate produced by pyrolysis at 600 oC with different amounts of TiO2 (UM600T5, UM600T10 and UM600T20) showed 79%, 80%, and 87% photodegradation efficiency.
  • Master Thesis
    A Comparative Study on the Photocatalytic Activity of Dye-Sensitized and Non-Sensitized Graphene Oxide-Ti̇o2 Composites Under Simulated and Direct Sunlight
    (01. Izmir Institute of Technology, 2019) İlhan, Hatice; Varlıklı, Canan; Demir, Mustafa Muammer
    Amine modified graphene oxide (mGO) and TiO2 composite was synthesized by low temperature hydrothermal method. Characterization of the synthesized material was carried out by using X-ray diffraction, X-ray photoelectron spectroscopy, and BET analysis techniques. The films of mGO:TiO2 and formerly synthesized TiO2, N-TiO2, GO-TiO2 and GO:N-TiO2 were fabricated by doctor blade method and employed as photocatalysts for the photodegradation of Rhodamine-B (RhB) dye under simulated (Xe lamb) and direct sun-light. P25 was also used as reference photocatalyst for all of the synthesized ones. Photodegradation of RhB was monitored by UV-Vis spectroscopy. Among all the catalysts, GO:N-TiO2, the composite of GO and N-doped TiO2, presented the best photocatalytic activity and although the activity of mGO:TiO2 was better than the activities of P25 and TiO2, it presented lower degradation rate constant even than that of the N-TiO2. It is proposed that increased abundance of C-C bonds and decreased number of oxygenated functional groups on mGO:TiO2, in addition to the morphological difference between GO (sheet like) and mGO (dot like) has great influence on their photocatalytic activities. Among the GO containing photocatalysts including mGO:TiO2, specific surface area (SSA) and number of RhB molecules per film volume were the lowest and particle size was the highest for mGO:TiO2. Although the number of RhB molecules per film volume was higher in mGO:TiO2 than that of the N-TiO2, it is thought that approximately 2 folds higher SSA of N-TiO2 allowed better photocatalytic performance. Additionally, the films were sensitized with PTE dye to obtain effective catalysts in visible region and reusability of the films were also tested. Degradation rate constants of all fabricated films have increased under both of the irradiation media and no significant change in rate constants were detected after the reusability tests.
  • Master Thesis
    The Effect of Metal Doping on Tio2 for Photocatalytic Applications
    (Izmir Institute of Technology, 2019) Alduran, Yeşim; Özyüzer, Lütfi; Öztürk, Orhan
    Recently, the photocatalysis method has been an active research area as a promising solution for environmental cleaning method, leading to self-cleaning and sterilization of solar cell surfaces to produce water dissociation reaction. Titanium dioxide (TiO2) is the most suitable semiconductor for photocatalytic applications due to its high oxidation potential and high efficiency when irradiated by ultraviolet light (UV). Undoped and Ruthenium (Ru+) doped TiO2 thin films were prepared using magnetron sputtering technique. All thin films were grown on SLG different ratios like 1 sec, 3 secs, 5 secs and 7 secs to set shutter position in magnetron sputter target. Transparent substrate SLG is coated with nearly 50 nm TiO2 thin films without compromising any optical properties. Samples were heat treated for two hours at 500°C to get the anatase phase crystal structure. The crystallization peaks of TiO2 are proved to get the anatase phase. Photocatalytic activity of TiO2 thin films are determined after 1, 3, 5 and 24 hours with organic pollution as a methylene blue dye degradation under UV light. The degradation of methylene blue was investigated kinetically and photocatalytic activity rate constants of the photocatalysts were calculated. All thin films could not reach super hydrophilicity state. Undoped TiO2 contact angle 47.309o and Ru doped TiO2 63.218o were evaluated. The photocatalytic degradation percentage of Methylene Blue was reached 87%, after 24 hours of UV irradiation, when using Ru-doped TiO2 thin film. Consequently, the anatase phase of Ru-doped TiO2 thin films are found best photocatalytic activity in self-cleaning performance.
  • Master Thesis
    The Investigation of the Water Splitting Activities of Coprecipitated Doped Nanotitania Powders
    (Izmir Institute of Technology, 2018) Gözel, Gözde; Çiftçioğlu, Muhsin
    The increase in the extent of greenhouse gases in earth’s atmosphere lies behind the global warming and climate change. The extensive use of unsustainable fossil fuels have intensified the greenhouse effect, causing global warming. Hydrogen is considered as an ideal fuel for the future. Hydrogen fuel can be produced from renewable energy sources and its life cycle is clean. Artificial photosynthesis has been considered as a promising prospect for the synthesis of renewable and sustainable fuels. Photocatalysis is expected to make a great contribution to environmental problems and renewable energy generation in the very near future. Titania based photocatalytic materials are one of the widely used materials in artificial photosynthesis research due to their unique chemical and optical properties. Photocatalytic water-splitting by using TiO2 based photocatalysts for hydrogen production offers a promising alternative for clean, low-cost and environmentally friendly production of hydrogen. ZrO2 doped TiO2 photocatalyst powders were prepared by coprecipitation and characterized in this work. The photocatalytic water splitting activities of these ZrO2 doped TiO2 photocatalyst powders in hydrogen production was investigated under UVVis light. The phase structures of the powders were significantly affected by the level of dopants and the primary particle sizes increased from about 130 nm to about 500 nm during heat treatments in the 550-700°C range. Maximum hydrogen yield of about 5000 μmol/hr gcat. was obtained with the 550°C heat treated powder doped at 0.1-0.1 mol% ZrO2-Nd2O3 level. ZrO2 doping above 10 mol% decreased the hydrogen yields of the catalysts to lower than 1000 μmol/hr gcat.
  • Master Thesis
    Electrochemical Properties of Titania Based Powders
    (Izmir Institute of Technology, 2015) Türkay, Cem; Demir, Mustafa Muammer; Çiftçioğlu, Muhsin
    Global warming arising from the greenhouse effect is globally accepted as the main problem which may threaten the life on the earth. Excess emission of carbon dioxide which leads to the more absorption of solar radiation in the atmosphere is the main reason for global warming. Carbon dioxide present in the atmosphere is balanced by natural photosynthesis; however this balance was disturbed by the increasing amount of carbon dioxide emissions after industrial revolution. Intense efforts was made by many scientists to find solutions to decrease the carbon dioxide level in the atmosphere and the pioneering studies were conducted in the early 1970s which founded the basic theory of artificial photosynthesis. The conceptual idea on conducting photosynthesis by technologically feasible processes was accepted by many scientists and the research on artificial photosynthesis accelerated in the last 10 years. The enhancement of the efficieny of artificial photosynthesis, by which alternative fuels such as methane, methanol may be produced, can be realized by doping titanium dioxide which is the most widely used photocatalyst in the literature. The determination of new electrochemical properties obtained by doping titanium dioxide is crucial since the oxidation/reduction reactions are controlled by the electrochemical structure of this material. Bandgap and band position energy levels which are important properties in photocatalysis can be determined and the efficiency of photoreduction under UV or visible light corresponding to these energy levels can be improved. Cyclic voltammetry (CV) can be used to determine the electrochemical properties of titanium dioxide and these properties can be improved by using the information obtained with this method. The effects of rare earth element doping on the electrochemical properties of titanium dioxide were investigated through out this Msc study. It was found that doping of titanium dioxide is significantly increased the electrochemical activity with rare earth elements. The increase in the doping amount of elements showed that articial photosynthesis activity of titanium dioxide may be enhanced by rare earth element doping.