Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
Browse
125 results
Search Results
Master Thesis Investigation of Electrochemical Co2 Capture System(Izmir Institute of Technology, 2022) Uzunlar, Erdal; Uzunlar, Erdal; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyFossil fuels have been used as a primary energy source for many years to meet the increasing energy demand since the industrial revolution. Fossil fuels are an important source of carbon that triggers global warming and climate change. To reduce the accumulation of carbon dioxide in the atmosphere, carbon capture has become more important. Conventional carbon capture technology is a thermally regenerated amine-based capture based on monoethanolamine (MEA). In this process, carbon dioxide is captured in an absorption column with the amine solution, and CO2-amine solution is sent to the stripping column, where the solution is heated to release the captured CO2 and regenerate the amine solution. However, an important disadvantage of this process is that it requires high energy for the CO2 release step. Recently, electrochemical CO2 capture process is proposed in the literature to decrease the energy requirement. The aim of this study is to investigate the electrochemical CO2 capture process using homopiperazine (HPZ). Unlike the conventional CO2 capture process, the CO2 release step is performed using an electrochemical cell. In the anode compartment of this electrochemical cell, the formed CO2-amine complexes are converted into amine-metal complexes from which the CO2 is released. The amine-metal complexes are then sent to the cathode, where the complex decomposes and metal deposition occurs. Laboratory-scale studies of the electrochemical capture process using MEA and HPZ as solvent were carried out. In the obtained results, it was found that HPZ has higher CO2 capture capacity and CO2 release rate than MEA and a similar CO2 absorption rate as MEA. In addition, UV-Vis spectra analyses showed that the reaction rate at the anode was much higher than the reaction rate at the cathode for both amines.Master Thesis Development of Keratin Based Hydrogel Systems(Izmir Institute of Technology, 2022) Top, Ayben; Top, Ayben; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study, keratin proteins from Merino sheep wool were obtained via oxidative extraction (Chapter 2), sulfitolysis extraction (Chapter 3) and sulfitolysis with reductive extraction methods (Chapter 4). Keratin proteins were characterized XRD and FTIR spectroscopy and thermal analysis. In the SDS-PAGE gel results of the keratins diffusive protein bands between ~23 kDa and >170 kDa and a discrete band at about 12 kDa were observed confirming highly polydisperse nature of the protein samples. Then, keratin-based hydrogel systems were obtained via different methodologies. In Chapter 2, oxidized keratins (keratoses) were crosslinked with THPC to form keratose hydrogels. Effect of the amount of the crosslinking agent on the viscoelastic, swelling, and morphological properties of hydrogels was investigated. In Chapter 3, the keratin hydrogels were obtained via reformation of disulfide bridge and self-assembly of the keratin chains. In Chapter 4, keratins reduced with DTT were crosslinked with 2000 Da PEG-(C2H4-mal)2 and 6000 Da PEG-(C2H4-mal)2 to prepare PEG-hydrogels. Storage moduli of the hydrogels were obtained in the range of 63 ± 22 and 2613 ± 254 Pa and were shown to be tuned by the amount and chain length of the crosslinker. The highest swelling ratios were obtained for the THPC crosslinked hydrogels whereas the highest pore size was observed in PEG-keratin hydrogels. Cytocompatibility of the keratin based hydrogel systems was confirmed using L929 mouse fibroblast cells by applying CCK-8 tests. Of these hydrogels, PEG-keratin hydrogels were found to support cell proliferation with a higher rate than empty TCPS wells up to 4 days. These results demonstrate that low-cost keratin-based hydrogels can be used in a variety of biomedical applications, such as drug delivery systems for cancer therapy, and scaffolds in wound healing and soft tissue engineering.Master Thesis Esterification of Free Fatty Acid Obtained From Waste Cooking Oil Over Solid Catalyst(Izmir Institute of Technology, 2022) Şeker, Erol; Şeker, Erol; Şeker, Erol; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe objective of this study was to investigate effect of reaction temperature, catalyst weight percentage and composition of Al2O3/SiO2 on conversion of FFA obtained from waste cooking oil (WCO) to take place esterification reaction by using Box-Behnken design. Statistical analysis demonstrates that catalyst weight percentage and temperature were insignificant statistically. Alumina composition was found as significant parameter at certain conditions by considering statistical analysis. It was seen that conversion of Free Fatty Acid (FFA) increases as composition of Al2O3 in Alumina/Silica catalyst increases. %80 Al2O3/20% SiO2 catalyst was found as promising catalyst since conversion of FFA with the catalyst was 32% at 80°C and 15:1 alcohol to FFA ratio. Besides, it was found that alcohol to FFA ratio affected the conversion reversely. When alcohol to FFA ratio was reduced to 2:1, conversion of FFA increased to 41%. The prepared catalysts were characterized by XRD and TPD analysis. Activity of catalysts were attributed to acidic strength and Bronsted acid sites on the aluminum sulfate in the catalysts. After screening effects of catalysts and reaction conditions, optimum levels of parameters were used to investigate the esterification reaction of model WCO. This reveals that conversion of FFA was found as 11% at 80°C and 15:1 alcohol to FFA ratio. Finally, the proposed catalyst does not have catalytic activity of hydrolysis reaction of oil at applied conditions.Master Thesis Anaerobic Digester Modelling for Production of Biogas From Waste Hazelnut Husk(Izmir Institute of Technology, 2022) Şeker, Erol; Şeker, Erol; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyAnaerobic digestion is a degradation process of complex organic matters into methane and carbon dioxide in an oxygen-free environment maintained by microorganisms. An advantage, besides energy production, is it is a waste management technique. Hazelnut husk is a valuable raw material for the anaerobic digestion process with more than 55 % cellulose and hemicellulose content. Anaerobic Digestion Model No. 1 (ADM1) developed by IWA Group was used in this study. This master thesis modeled biogas production by co-digestion of cattle manure and hazelnut husk process in MATLAB. The goal was to evaluate the methane amount of a household bioreactor. Tanks-in-series model with 3 CSTRs was chosen after residence time distribution (RTD) analysis. Ten different cases were investigated to show the effects of carbon source/manure ratio, temperature, carbon source type, total solid (TS) amount, reactor type, and RTD analysis. The carbon source/manure ratio improves the methane yield as it increases. When the ratio is 1, methane yield is 0.229 L/kgVS whilst yield is 0.224 L/kgVS if the ratio is 0.1. The temperature effect on the process is significant. In the thermophilic case, the methane production is 0.432 L/d which is the highest amount compared to mesophilic and psychrophilic cases. When food waste is used as a carbon source with a ratio of food waste/manure of 0.1, the methane production is 0.410 L/d while it is 0.403 L/d in hazelnut husk digester. When the TS amount is doubled, the methane yield goes down from 0.224 to 0.149 L/kgVS because the residence time is not long enough to digest it as well as in case with lower total organic carbon level. In unmixed, mixed, and Chinese Dome Digester types of reactors, methane productions are 0.403, 0.646, and 0.552 L/d, respectively. In the ideal case, the methane production is 1.525 L/d which indicates the necessity of RTD analysis.Master Thesis Devlopment of Solid Acid Catalysts for Cellulose Acetate Production(Izmir Institute of Technology, 2022) Yılmaz, Selahattin; Yılmaz, Selahattin; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyCellulose acetate (CA) is one of the most commercially important cellulose derivatives with a wide range of applications in various industries. As a green approach, the development of heterogeneous solid acid catalysts for cellulose acetate production is important. The objective of the present thesis is to develop active and stable mesoporous solid acid catalysts for solventless cellulose acetate production with acetic anhydride from microcrystalline cellulose. As catalyst sulfating agents, ammonium sulfate and chlorosulfonic acid (CSA) were applied. Ammonium sulfate ((NH₄)₂SO₄) sulfated catalysts are La incorporated titania-silica (SO4/La-TiO2-SiO2), sulfated titania-silica (SO4/TiO2-SiO2), and sulfated Ti-SBA-15 (SO4/Ti-SBA-15), whereas the CSA/Ti-SBA-15 catalysts were sulfated by chlorosulfonic acid. The effect of Si/Ti mole ratios (6, 10, 20) on the stability of CSA/Ti-SBA-15 catalysts was investigated. Activity and stability of the catalysts were tested in the cellulose acetylation reaction by acetic anhydride at 80 oC with a 10:1 acetic anhydride to cellulose AGU mole ratio. The effect of reaction time (2, 4, 6, and 8 h) and amount of catalyst (0.10, 0.25, and 0.5 g) on the reaction were investigated. Synthesized cellulose acetate samples were analyzed by FT-IR, 1H-NMR, and TGA. CSA/Ti-SBA-15 (10) was found to be the most active and stable catalyst with 2.84 % leaching, 89.6 % conversion, 74.6 % yield, and DS of 2.69. The activity and stability of CSA/Ti-SBA-15 (10) catalyst were further investigated after its treatment with acetone. At the end of the 3rd cycle, A-CSA/Ti-SBA-15 (10) was found as an active and stable catalyst with 58.6% cellulose conversion, 50% CA yield, DS of 2.62, and 1.68% sulfur leaching.Master Thesis An Investigation of Data-Based Fault Detection Methods in Petroleum Refineries(Izmir Institute of Technology, 2022) Uzunlar, Erdal; Uzunlar, Erdal; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe petroleum refineries are complex systems vital for energy and production sectors. During production, these complex systems might experience various faults, including fluid leaks in unit operations. The detection of leaks is important for a reliable, safe, and efficient operation. Among the possible leak detection mechanisms, data-based leak detection methods are promising in terms of low investment cost, less human intervention, ability to detect small leaks in advance and direct integration capability to distributed control systems. The aim of this study is to investigate data-based leak detection methods in a heat exchanger in a petroleum refinery. To that end, possible leaking problems in petroleum refineries are assessed, multiple leak cases from a real heat exchanger in a petroleum refinery are determined, literature studies are searched for appropriate data-based leak detection methods, applicability of a set of data-based leak detection methods is studied with a literature benchmark data set, and the real cases of heat exchanger leaks are studied with the determined leak detection methods. Data sets for multiple leak cases of a heat exchanger are obtained from a TUPRAS refinery. The benchmark data set is obtained from Tennessee Eastman Process (TEP). Discrete Wavelet Transform (DWT), Auto Encoder (AE), and Exponentially Weighted Moving Average (EWMA) are selected as the data-based leak detection methods. The selected data-based methods are first studied with TEP data set, and good fault detection capability is observed. Then, the real leak cases are studied. All three data-based methods are found successful in detecting the actual leak cases. For some of the cases, leaks are detected with data-based methods in advance of the operation engineers noticing the leak.Master Thesis Modification of Corn Starch by Oxidation and Acetylation(Izmir Institute of Technology, 2022) Yılmaz, Selahattin; Yılmaz, Selahattin; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyMore sustainable and eco-efficiency industries intend to use bio-based raw materials instead of petroleum-based raw materials. Starch is one of the most useful, easily accessible, and cheap bio-based raw materials in the industry. This study aimed to produce modified starch that had proper solution viscosity for coating and low gelling enthalpy to reduce production energy for the adhesive industry. Corn starch was modified by oxidation with sodium hypochlorite (NaOCl), acetylation with acetic anhydride (AA), and a combination of the two (dual modification). The effect of different amounts of oxidants (6.0, 12.0, and 24.0 g Cl/ kg starch) and acetylation agents 7.50, 15.0, 30.0 g AA) on the properties of corn starch was examined at room temperature. The structural characteristics of starch granules were assessed using FTIR, 1H-NMR, DSC, solution viscosity, light transmittance, and SEM microphotographs. The effectiveness values that were identified as carbonyl and carboxyl percentage and degree of substitution (DS) in modified starches were determined. The results showed that increasing oxidant concentration increased the carbonyl and carboxyl percentage to 0.0061 % and 1.33 % but acetyl groups were independent from increasing acetic anhydride concentration. Oxidation had a superior reduction effect on starch solution viscosity with 42% reduction when compared to 22% reduction with acetylation. Both processes reduced the gelling enthalpy, but double modification was more effective. Acetylation had a greater effect on light transmittance. Surface morphology of starch was only affected by active chlorine content at 24.0 g Cl/ kg starch, but all acetic anhydride amounts caused the changes.Master Thesis Production of Butyl Glucosides by Zr-Sba & So4/Zr-sba-15 Catalysts(Izmir Institute of Technology, 2020) Yılmaz, Selahattin; Yılmaz, Selahattin; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe purpose of this study was to develop mesoporous solid acid catalyst for glycosidation reaction of butanol. Therefore, Zr incorporated SBA-15 silica materials with two different amount of zirconia loadings were prepared by hydrothermal synthesis. In addition to them, sulfate modified forms (SO/Zr-SBA-15) were prepared by treating Zr-SBA-15 catalysts in 0.5 M and 1.0 M H2SO4 solutions respectively. These 6 catalysts were tested in the glycosidation of butanol and as product butyl glucosides were produced. The reaction tests were carried out in a 100 ml glass reactor at 117°C. Catalysts properties were determined by different characterization techniques. The analysis showed that mesoporous, acidic catalysts were obtained and zirconium was incorporated into SBA-15 structure. While the surface area and pore diameter decreased by higher zirconium loading and sulfonation, acidity of the catalysts increased. The highest acidity was observed in 1.0 SO/Zr-SBA-15-(1.0) catalyst. The formation of butyl glucosides was determined by HPLC analysis. Results showed that activity of the catalysts were different for the glycosidation reaction of butanol. The highest butyl glucoside yield was obtained with 1.0 SO/Zr-SBA-15-(1.0) catalyst, while the lowest yield was obtained with Zr-SBA-15-(1.0) catalyst. This was attributed to the higher acidity (2.35 mmol NH3/g cat.) and B/L ratio (1.97) of 1.0 SO/Zr-SBA-15-(1.0) catalyst with respect to the others. The reusability tests were performed up to 2 times for the catalyst with the best results. There was no major decrease (7%) in the product yields and this confirmed the stability and reusability of the catalysts.Master Thesis Epoxidation of Soybean Oil Over Mesoporous Titanium and Niobium Incorporated Sba-15 Catalysts(Izmir Institute of Technology, 2019) Kalkandelen, Mustafa; Yılmaz, Selahattin; Yılmaz, Selahattin; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologySoybean oil is an abundant, cheap and nontoxic biomass source and contains triglycerides with unsaturated fatty acids which can be easily modified by epoxidation. In this study, mesoporous Ti-SBA-15 with two different Si/Ti molar ratios, MoO3/Ti-SBA-15 with two different MoO3 mass ratios and Nb-SBA-15 with two different Si/Nb molar ratios were prepared as catalysts for soybean oil epoxidation reactions. Tertbutanol and ethyl acetate was used as solvent and H2O2 was utilized as oxidant. BET analysis indicated existence of high surface area of the catalysts which ranged between 650 and 950 m2/g. XRD analysis indicated successful incorporation of Nb and Ti into SBA-15 structure. Epoxidation reactions were carried out successfully using Ti-SBA-15 and Nb-SBA-15 catalysts in tertbutanol at 75 ºC for 6 h. Utilizing ethyl acetate as solvent was caused undesired catalyst behaviour such as precipitation, gelation and aggradation. No further investigations were carried out with ethyl acetate. Epoxidation products were analysed with H-NMR, FTIR and analytic methods. Ti-SBA-15 catalysts provided only 10 % double bond conversion and 49 % epoxide selectivity. They were not very active. Nb-SBA-15 catalysts exhibited high acidity. They provided 28 % double bond conversion and 31 % epoxide selectivity. Best yield was obtained with Nb-SBA-15 (10) catalyst as 6.49 %. Stability tests of catalysts indicated that Nb and Ti did not leach whereas severe leaching was observed with Mo. Also, homogenous epoxidation reaction with H2SO4 was carried out for comparison with heterogenous catalysts. Results indicated that, heterogenous catalysts were not competitive with homogenous catalyst.Master Thesis The Influence of Inorganic and Organic Coating Layers on the Corrosion Behaviour of Coil Coated Aluminum Substrates(Izmir Institute of Technology, 2020) Uç, Merve; Kızılkaya, Ali Can; Kızılkaya, Ali Can; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyOrganic coil coated aluminum substrates are one of the most widely used materials for construction industry. These coated substrates typically consist of 4 separate layers, the aluminum substrate, the inorganic conversion coating (resulting from the pretreatment application), and the organic coating layers that are called the primer and the topcoat. From industrial experience, it is not clearly and quantitatively determined how these layers contribute to the different processes that occur during corrosion, such as water uptake (diffusion of water through the coating) and the corrosion reactions that take place on the substrate. In this thesis, the formation of the inorganic conversion coating as a function of the pretreatment application parameters, immersion time, temperature and pH, and the individual effects of inorganic and organic coating layers on corrosion are investigated. The structure of the various surfaces formed after coating application and after corrosion testing by Neutral Salt Spray Test (NSST) is investigated by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), X-ray Fluorensence Spectrometer (XRF) and Atomic Force Microscopy (AFM) analysis, while their anticorrosive properties are determined by Electrochemical Impedance Spectroscopy (EIS). The results indicate that the formation of the pretreatment layer is enhanced continuously as function of temperature and immersion time, within the values investigated, while for pH an optimum is observed. The investigation of the corrosion resistance of substrates coated with different coating layers reveal that without organic coating layers, the substrates corrode much faster, indicating the importance of water diffusion on the corrosion reactions.