Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Detailed Chemical Kinetic Modeling of N-Heptane Flame(Izmir Institute of Technology, 2018) Değirmenci, Emre; İnal, FikretTo understand the complex combustion characteristics of gasoline, n-heptane is used as one of the two major reference fuels. The emissions resulted from incomplete combustion are one of the main issues caused from usage of high amount of fossil fuels in transportation and energy generation sectors. The main purpose of this study is to model one-dimensional premixed, laminar, burner-stabilized fuel-rich n-heptane flame to understand its combustion characteristics in mainly fuel-rich conditions. Detailed chemical kinetic modeling technique was used to get high amount of information about the ignition characteristics of n-heptane and formation nature of emissions. A detailed chemical kinetic mechanism was generated by combining several mechanisms from the literature that related with possible products of fuel-rich n-heptane combustion. The detailed mechanism consists of 4185 reactions and 893 species. Validations of the model were done with various experimental data available in the literature such as premixed laminar flames and jet stirred reactors. After generating the kinetic model, detailed investigation of the n-heptane flame was done by using rate of production, reaction sensitivity and reaction pathway analyses. One of the attributes of fuel-rich flames, Polycyclic aromatic hydrocarbon (PAH) formation kinetics were also investigated. Acetylene (C2H2), propargyl radical (C3H3), and vinylacetylene (C4H4) were found as the main precursors of the first aromatic ring and PAH formation as a result of pathway and rate of production analyses. The generated model was able to predict most of the major, minor and trace components that formed in the flame that modeled. A reduced model was also generated by using directed relation graph with error propagation (DRGEP) mechanism reduction technique on the detailed mechanism. The reduced mechanism consists of 1879 reactions and 359 species. The species mole fraction predictions of detailed and reduced mechanism were very close to each other. Most of the species formed in the flame were predicted by the reduced mechanism with less computational afford than detailed mechanism.Master Thesis Desing and Synthesis of Fluorescein Based Gold Ion Sensors(Izmir Institute of Technology, 2016) Çetintaş, Ceyla; Emrullahoğlu, MustafaGold has been a part of people’s lives for ages and is used as money, goods and jewellery. In recent years, gold has played a key role in chemistry, medicine and biology. Since the 1970s, gold has been extensively used as a catalyst in several chemical transformations. Due to its high biocompatibility, functionalized gold nanoparticles have been extensively employed as drug and gene delivery systems, biosensors and bio-imaging materials. However, gold complexes can become toxic to the human body by interacting with biomolecules such as DNA and enzymes. Therefore, detection of trace amounts of gold species is an important issue and can be achieved via spectroscopic methods such as atomic absorption spectroscopy, atomic emission spectroscopy and inductively coupled plasma spectrometry. However, these analytical methods require complicated sample preparation steps and sophisticated instrumentation. In contrast to these extremely expensive and time-consuming methods, fluorogenic or chromogenic methods, which provide high analyte sensitivity and selectivity, can serve as good alternatives for detecting gold species. To develop new probes for the detection of Au3+ ions, we focused on the design of new fluorescein-based probes that are soluble in aqueous media. We aimed to investigate the in vivo activity of these fluorescent probes. In the proposed detection system, gold ions are expected to mediate a chemical reaction through coordination to an alkyne moiety that results in a ring opening reaction to yield a highly fluorescent derivative.Master Thesis Catalytic Methanol Combustion(Izmir Institute of Technology, 2015) Demirkaya, Emre; Şeker, ErolThroughout this study, the major goal is to analyze the product distribution of methanol combustion at different reaction conditions, such as, varying space velocities, different initial temperatures, on 2% Pt/Al2O3 catalyst. The catalyst support material, alumina, was prepared by using a single-step sol-gel method and platinum was added by using the impregnation method. The reaction was conducted in a tubular reactor. In this work, the maximum steady state temperature at room temperature experiment was achieved almost same within the error for 2.4 s-1 and 2.8 s-1 space velocity for fresh catalyst, and also, the conversion to CO2 during the methanol combustion reaction for all the space velocities (2.4 s-1, 2.8 s-1 and 3.1 s-1) were found to be ~100%. Another parameter that was studied was the temperatures below the room temperature. The reaction was performed at -13oC, 0oC, 7oC and 15oC temperatures. With decreasing initial temperature, the steady state temperature was also found to be decrease. This was correlated with the product distribution and with decreasing initial temperature, CO2 conversion decrement was observed.. Methyl formate was detected to be the main byproduct that was produced under all the space velocities at temperatures lower than room temperatures. The catalyst was active even at -13oC. Therefore, it showed that it could be used as a catalyst for an external heater to provide necessary heat to reach the direct methanol fuel cells operating temperature at and below room temperature. Other than the other catalysts that was investigated in literature, our catalyst does not need to heat up the reactor. Once the fuel is supplied, the system reaches the necessary operating temperature by itself. This is desirable especially in portable DMFCs. The catalytic methanol combustion system investigated in this study seems to be promising to easily replace the lithium-ion batteries for portable electronic systems, especially ones used in the military.Master Thesis Investigation of the Reaction of Boron Oxide With Aluminium Powder and Method Development for Boron Determination in the Reaction Mixture(İzmir Institute of Technolog, 2007) Demirsar, Yelda; Özgen, TamerkanIn this study, a cheap method for the synthesis of elemental boron by the reduction of boron oxide with aluminum was investigated. However after various optimization studies, detectable boron amounts could not be found in the reaction mixtures by XRD and SEM-EDX analysis. Meanly aluminum borates were formed as products and these products were leached by 6 M HCl, however removel of borates could not be achieved. We think that the reason of this outcome is that we worked with simple experimental setup, therefore could not achieving the suitable experiment conditions and because of this we failed in the sythesis of boron. In the second part of the study, a new method for the direct determination of boron was investigated. 96 %pure boron and KBr were mixed and analyzed with Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). No distinct differences for boron was observed in the DRIFT spectra. Then, different sample compositions were prepared with different amounts of boron and KBr. These samples were split as validation and calibration sets and their spectra were collected by DRIFTS. All collected spectral data were processed in a different computer where the data proccessing programs were installed. The genetic inverse least square (GILS) method was used inorder to generate calibration model. Results obtained showed that boron amounts could be directly determined with maximum 3-4 % error. Afterwards, same procedure was also tried for boron and boron oxide binary mixtures and boron, boron oxide and aluminum ternary mixtures. In the binary mixture, determination of boron could be successfully achieved, however boron oxide determination could not be achieved as good as boron determination. In the ternary mixture, better results were obtained compared to binary mixture. Finally, the method was tried with the original samples, but not very satisfactory results were obtained. We think this result is due to the malfunction of FTIR instrument and personal error in the preparation of similar samples. More sample preparation and measurement could not be achieved because the FTIR instrument is not functioning at present.Master Thesis Physiological and Biochemical Characterization of Drought Tolerance in Chickpea(Izmir Institute of Technology, 2012) Keskin, Hilal; Frary, AnneChickpea (Cicer arietinum cv. Gokce.) is an agronomically and economically significant plant for Turkey. It is successfully grown under severe drought conditions which limit the growth of other plants. It is generally affected by terminal drought which causes retardation of flowering and decreases yield in Mediterranean and subtropical climates. The aim of this study was to determine significant factors which can be used to identify chickpea plant tolerance to drought stress. With this objective we assessed physiological (fresh and dry weight, relative and real water content) and biochemical (enzymatic and non-enzymatic antioxidants, malondialdehyde, total protein and phytohormone contents) parameters which were used to measure the impact of drought on chickpea. To determine drought's effects, we collected stressed (drought treated) and control (non drought treated) samples from the chickpea cultivar Gokce. Results showed that both fresh and dry weights of plants increased while real and relative water contents of plants decreased under drought stress. There was an increase in both malondialdehyde (MDA) and total protein contents under drought stress. Furthermore, glutathione reductase (GR) and catalese (CAT) enzyme activity increased in drought treated plants whereas guaiacol peroxidase (POD) and superoxide dismutase (SOD) enzyme activity decreased. Moreover, contents of indole acetic acid (IAA) and abscisic acid (ABA) increased in all tissue parts while contents of salicylic acid (SA), gibberellic acid (GA) and jasmonic acid (JA) increased in specific plant tissue parts during drought treatment. In conclusion it is obvious that all of these characters play essential roles in the drought tolerance of plants.Master Thesis Suzuki Reactions Over Palladium Loaded Y Zeolite(Izmir Institute of Technology, 2002) Bulut Güllübağ, Hatice; Artok, LeventIn this study, the use of Pd(II) loaded NaY type zeolite as a catalyst in the Suzukiinvestigated.For this aim, Pd(OAc)2, and [Pd(NH3)4]Cl2 complexes were loaded into NaY zeolite in order to form an appropriate catalyst system. Pd(NH3)42+ loaded Y type zeolite was calcined to obtain Pd(II) form Pd(OAc)2 loaded Y type zeolite showed high activity in the reactions of 4-iodoanisole and 4-bromoanisole with arylboronic acid. However the reusability which is an important property of heterogeneous catalyst could not be provided, the following studies were continued with Pd(II) loaded Y type zeolite.When, 4-iodo and 4-bromoanisole reactives were used in the presence of Pd(II) loaded Y type zeolite, 60-100% biaryl products were obtained. The amount and type of the base and DMF:H2O ratio have high effects on the yield. In order to prove that the reaction took place in heterogeneous phase, at the end of the reaction Pd analysis of the solution was performed by AAS technique. It was found that the Pd amount in solution was trace.