Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Development of Biosensors for Determination of the Total Antioxidant Capacity(Izmir Institute of Technology, 2008) Çoban, Seçil; Bayraktar, Oğuz; Bayraktar, Oğuz; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study, an amperometric laccase biosensor was developed for determination of the oleuropein concentration that is the biological active component of olive leaf and contributes dominantly to the total antioxidant capacity. The biosensor was prepared by immobilization of laccase from Trametes versicolor by addition of cross-linking agent, glutaraldehyde, into the carbon paste electrode. Different biosensors were prepared by changing the amount of crosslinking agent and concentration of the enzyme solution. So, effect of these parameters on biosensor performance was investigated. The best biosensor performance was determined for the biosensor having glutaraldehyde amount of 12.03 % vol. of the biosensor bottom part and 5 mg/ml of laccase enzyme. The effect of scan rate and temperature on the biosensor performance was also investigated in this study. The scan rate of 10 mV/s was decided to be the optimum for the amperometric detection of oleuropein considering the fastest response and maximum reduction current. 250C was chosen as an optimum temperature value due to the maximum laccase activity and capability of oleuropein acting as an antioxidant. Extraction of phenolics from olive leaf was also an important part of this study. The extract was divided into fractions varying in their oleuropein amounts such as polar fractions and relatively less polar fractions. Therefore, biosensor performance was investigated for fractions containing different type of phenolics. HPLC analyses of the fractions were also performed in this study. In addition total phenol content and antioxidant capacity of the fractions were determined by conventional methods.Master Thesis Ion exchange in natural zeolite packed column(Izmir Institute of Technology, 2004) Can, Özge; Ülkü, Semra; Can, Özge; Ülkü, Semra; 03.01. Department of Bioengineering; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyTurkish natural clinoptilolites were examined to evaluate their ion exchange performance for the removal of copper, nickel and cobalt ions by performing both batch and packed column experiments.Initial metal solutions were prepared using metal nitrate solutions at various concentrations.All of the experiments were carried out at 29oC.Before performing the ion exchange experiments zeolites were characterized and their clinoptilolite contents were determined quantitatively as 80 and 64 % for zeolites named as CP1 and CP2, respectively.The copper exchange capacities of CP1 and CP2 were determined from equilibrium studies as 10.01 mg (0.32 meq) Cu2+ / g CP1 and 8.33 mg (0.262 meq) Cu2+ / g CP2. Ion exchange capacity of CP2 zeolite was determined as 6.64 mg (0.226 meq) Ni2+ / g and 4.55 mg (0.154 meq) Co2+ / g.The equilibrium behaviour of the system was best described by Langmuir model.Experiments were designed to investigate the optimum parameters and significance of the interactions between these parameters.In column studies, the parameters such as packing height, inlet metal concentration and flow rate were investigated.The concentration of the metals in the sample solutions which were taken from the exit of the ion exchange column at specific time intervals were analyzed by using Optical Emission Spectrometry (ICP-OES).Afterwards, by making use of the data obtained from ICP-OES, breakthrough curves were constructed.By the help of these curves, breakthrough capacity and ion exchange capacity of natural zeolites were calculated.The ion exchange capacity of CP2 zeolite was calculated as 8.04 mg Cu2+/g CP2, which was consistent with the capacity calculated from batch experiments, 8.33 mg Cu2+/g CP2.Also, breakthrough points were determined. Furthermore, solid phase was also analysed for determining its crystal structure and chemical composition using Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) devices (Philips XL 30S FEG).In addition to these, natural zeolite particles which have been ion exchanged throughout this process were regenerated using 0.2M and 1.7M of NaCl solutions.According to regeneration studies, it was determined that 94 and 95% of copper were recovered within the first 100 minutes for both experiments.After the experiments were performed, model equations were applied to the system in order to be able to investigate the dynamic behavior of the system.As a result of this simulation, breakthrough was well predicted.Master Thesis Control, Optimization and Monitoring of Portland Cement (pc 42.5) Quality at the Ball Mill(Izmir Institute of Technology, 2006) Avşar, Hakan; Doymaz, Fuat; Doymaz, Fuat; Doymaz, Fuat; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study, artificial neural networks (ANN) and fuzzy logic models were developed to model relationship among cement mill operational parameters. The response variable was weight percentage of product residue on 32-micrometer sieve (or fineness), while the input parameters were revolution percent, falofon percentage, and the elevator amperage (amps), which exhibits elevator charge to the separator. The process data collected from a local plant, Cimenta Cement Factory, in 2004, were used in model construction and testing. First, ANN (Artificial Neural Network) model was constructed. A feed forward network type with one input layer including 3 input parameters, two hidden layer, and one output layer including residue percentage on 32 micrometer sieve as an output parameter was constructed. After testing the model, it was detected that the model.s ability to predict the residue on 32-micrometer sieve (fineness) was successful (Correlation coefficient is 0.92). By detailed analysis of values of parameters of ANN model.s contour plots, Mamdani type fuzzy rule set in the fuzzy model on MatLAB was created. There were three parameters and three levels, and then there were third power of three (27) rules. In this study, we constructed mix of Z type, S type and gaussian type membership functions of the input parameters and response. By help of fuzzy toolbox of MatLAB, the residue percentage on 32-micrometer sieve (fineness) was predicted. Finally, It was found that the model had a correlation coefficient of 0.76. The utility of the ANN and fuzzy models created in this study was in the potential ability of the process engineers to control processing parameters to accomplish the desired cement fineness levels. In the second part of the study, a quantitative procedure for monitoring and evaluating cement milling process performance was described. Some control charts such as CUSUM (Cumulative Sum) and EWMA (Exponentially Weighted Moving Average) charts were used to monitor the cement fineness by using historical data. As a result, it is found that CUSUM and EWMA control charts can be easily used in the cement milling process monitoring in order to detect small shifts in 32-micrometer fineness, percentage by weight, in shorter sampling time interval.Master Thesis Monitoring and Assessment of Indoor Air Volatile Organic Compound Concentrations in Primary Schools(Izmir Institute of Technology, 2008) Aslan, Güler; Sofuoğlu, Sait Cemil; Sofuoğlu, Sait Cemil; 03.07. Department of Environmental Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIndoor air quality (IAQ) is important mainly because, poor IAQ may cause variety of adverse health effects and people spend majority of their time indoors. One of the most susceptible groups to air pollution is considered as children. Children spend approximately six to eight hours a day in school buildings, therefore the indoor air quality of school buildings should be given utmost importance. Formaldehyde and volatile organic compounds (VOCs) have been receiving considerable interest in indoor air field studies because of their high emission rates from products used indoor environments. Thus, their concentrations have been measured in school buildings in many different countries.Indoor and outdoor air samples were collected from three primary schools in İzmir (School 1, School 2, and School 3). Sampling was performed in spring and winter terms. Active sampling was applied for VOCs and formaldehyde by using Tenax TA and DNPH silica gel sorbent tubes, respectively. VOCs were analyzed by using a thermal desorption - gas chromatography - mass spectrometry (TD-GC-MS) system.Formaldehyde analysis was performed by using an HPLC instrument.Benzene, toluene, ethyl benzene and xylenes, which have high toxicity, were detected at high concentrations. In addition, the indoor/outdoor (I/O) concentration ratios of VOCs were investigated. Mean Total VOC (TVOC) and formaldehyde concentrations were calculated for the three schools in winter and spring terms. TVOC and formaldehyde concentrations were 104 .g/m3 and 44.36 ./m3 in winter, and 66.42 .g/m3 and 43.73 .g/m3 in spring terms for School 1; and 50.86 .g/m3 and 30.78 .g/m3 in winter, and 32.1 .g/m3 and 35.82 .g/m3 in spring term for School 2, and 51.09 .g/m3 and 36.53 .g/m3 in spring term for School 3 primary schools, respectively. These concentration values are generally higher than or parallel to the values reported in the literature. The TVOC concentrations in kindergartens were higher than the concentrations in classrooms.Master Thesis Modeling of Hemodialysis Operation(Izmir Institute of Technology, 2008) Abacı, Hasan Erbil; Alsoy Altınkaya, Sacide; Alsoy Altınkaya, Sacide; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyRecent studies have shown that the effectiveness of hemodialysis is based on module geometry, membrane properties and operating conditions. Various experimental work exist in the literature concentrated on the synthesis of new hemodialysis membranes. However, optimization of membrane structure requires extensive and time consuming experimentations. Therefore, mathematical models are neccessary that can be used to predict the performance of hemodialysis operation. In this study, a predictive theoretical model was developed to predict the solute concentrations in patient.s blood and optimize the efficiency of hemodialysis operation. The model takes into account simultaneous mass and momentum transfer along with the adsorption of rejected protein molecules on the surface of the membrane.Model predictions show that blood and dialysate flowrates are effective for all sizes of molecules. The change in structural properties of the membrane makes no effect on the total removal of urea beacause of its high clearance. On the other hand, a considerable increment in the clearance of larger molecular weight solutes occurs as the pore size and porosity of the membrane increases. The most important design parameter for dialysis unit which influence the solute clearances significantly is found to be the effective diameter among the fibers in the dialyzer.The model is extended to investigate the use of urease immobilized membranes on the efficiency of the hemodialysis operation. The results have shown that urease immobilization enhances the removal of urea from the blood and decreases the protein adsorption capacity of the polysulfone membrane.Model predictions are compared with different sets of clearance data available in the literature. The agreement is found to be satisfactory which suggests that the model can be used as a tool to design or test the performance of dialysis units.Master Thesis Application of Zeolites in Biotechnology: Protein Adsorption(Izmir Institute of Technology, 1998) Özgü, Şebnem Karasu; Ülkü, Semra; Ülkü, Semra; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyRecovery of proteins from vanous culture broths is a complex engmeenng problem, involving multi-step schemes that lead to significant loss of the desired bioproduct by conventional methods. The bioproduct is not only present in very low concentrations, but also it is subject to chemical/enzymatic degradation. An alternative cost-effective method for recovery of proteins in a highly purified form may be through adsorption, which is a separation technique based on specific and reversible binding, with the use of zeolites that have favorable adsorption characteristics over the other adsorbents. Protein adsorption characteristics of a natural zeolite (clinoptilolite from Turkey) and a synthetic (3A) zeolite were determined through various experiments, altering parameters as pH (range 3.5-6), the amount of zeolites used for adsorption (0.01-0.05 g/ml) and the initial protein concentration (0.01-0.1%). Within the concentration and pH ranges studied, the adsorption capacity of the zeolites was around 50 mg protein/g zeolite. For natural zeolite, approximately 98% was adsorbed within the first 2 minutes, while for the synthetic zeolite, 70% was adsorbed within the first 15 minutes. Uptake diagrams were obtained, adsorption isotherms were determined and Langmuir method was used to describe the isotherms. Desorption was also investigated after treating the zeolites with salt and acid, but further work is necessary for obtaining better recovery. It can be concluded that clinoptilolite is capable of adsorbing proteins in a short time. This study may be the preliminary step, followed by further laboratory work and necessary scale-up experiments, towards the use of zeolites in the recovery of proteins in industry as an alternative to conventional methods.Master Thesis Measurement and Modeling of Thermodynamic and Kinetic Data of Membrane Forming Systems(Izmir Institute of Technology, 2007) Arslan, Mine Özge; Alsoy Altınkaya, Sacide; Alsoy Altınkaya, Sacide; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyPhase inversion process involving a ternary system (nonsolvent/solvent/ polymer) isfrequently used to prepare porous and asymmetric polymeric membranes. The thermodynamic and kinetic data for the ternary system are required to understand membrane formation mechanisms, change the preparation conditions and predict the final structure of the membranes. In this study, cloud point curves for polysulfone (PSf)/1-methyl-2-pyrrolidinone (NMP)/water, PSf/tetrahydrofurane (THF)/water, PSf/NMP/ethanol, PSf/THF/ethanol, polymethyl methacrylate (PMMA)/acetone/water, PMMA/ THF/water, PMMA/acetone/formamide and PMMA/THF/formamide systems were measured by titrating polymer solutions with nonsolvents until the onset of turbidity.Binodal curves were calculated by using the Flory Huggins theory with constant interactionparameters. Theoretical ternary phase diagrams were found to be in good agreement with experimental cloud point data. In addition to liquid liquid equilibrium data, sorptionisotherms and diffusion coefficients of water, ethanol and chloroform were measured byusing a magnetic suspension balance. Results of kinetic studies have shown that water sorption in PSf films exhibits Fickian diffusion while anomalous diffusion is observed for ethanol and chloroform sorption. The kinetic data for water sorption was analyzed using a simple Fickian diffusion model to determine the diffusion coefficients. On the other hand, anamalous sorption kinetics were interpreted by a mathematical model involving independent contributions from Fickian diffusion and polymer relaxations. The model successfully fits non-Fickian anomalies including sorption overshoot and allows to determine diffusion coefficients and relaxation times. Diffusivities of penetrants in PSf was found to decrease in the following order: Water > Chloroform > Ethanol. Equilibrium sorption isotherms of ethanol and chloroform are well described by classical Flory Huggins thermodynamic theory with constant interaction parameters. A modified version of this theory for concentration dependent interaction parameter is used to correlate the sorption isotherm of water. Vrentas Duda free volume theory is able to correlate diffusivity data of water collected at 30 C and 40 C while the theory fails to correlate the diffusivities of ethanol and chloroform both of which were determined from diffusion-relaxation model.Master Thesis Methyl Ester Production From Vegetable Oils on Heterogeneous Basic Catalysts(Izmir Institute of Technology, 2008) Umdu, Emin Selahattin; Şeker, Erol; Şeker, Erol; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study, the activities of heterogeneous mixed oxide catalysts; magnesium and calcium oxide on alumina and silica supports were investigated for transesterification of vegetable oils; canola and sunflower, to methyl esters. The primary objective of this study is to understand whether basicity of the solid catalysts and/or its crystallite size affect the biodiesel yield during the reaction. The mixed oxide catalysts were prepared by a single step sol-gel method. Magnesium oxide (MgO) and calcium oxide (CaO) were chosen because of their basic property.This study shows that the crystallite size does not have any direct effect on the transesterification activity. Yet, the interaction of the crystallites with the support material may change the number of the active sites and/or the creation of new .basic. sites. In fact, the basicity was found as the critical factor for the choice of the suitable mixed oxide for the transesterification reaction. The addition of CaO to alumina creates synergetic effect. But this is not observed with the catalysts: CaO/SiO2 and also the MgO/Al2O3 and MgO/SiO2.CaO/Al2O3 differs from the others in such a way that it contains the basic sites with the mild basic strength. Not only the crystallite size but also the type of the oxide is important to obtain the heterogeneous catalysts as active as the homogeneous catalyst. CaO/Al2O3 has the same activity as that of NaOH for the transesterification of canola and sunflower oils at 50 oC. It was also found that the activity of CaO/Al2O3 was truly heterogeneous.Master Thesis Preparation and Characterization of Antimicrobial Polymeric Films for Food Packaging Applications(Izmir Institute of Technology, 2007) Gemili, Seyhun; Alsoy Altınkaya, Sacide; Alsoy Altınkaya, Sacide; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study, cellulose acetate (CA) based antimicrobial packaging materials containing lysozyme as an antimicrobial additive were developed. In order to achieve appropriate controlled release of antimicrobial agent, the structure of the films were changed from highly asymmetric and porous to dense ones by modulating the composition of the initial casting solution. The effectiveness of the films were then tested through measurement of soluble and immobilized lysozyme activity, release kinetics and antimicrobial activity on selected microorganisms. The highest release rate, soluble lysozyme activity and resulting antimicrobial activity (on E.coli) was obtained with the film prepared from 5 % CA solution including 1.5 % lysozyme. Increasing CA content in the casting solution decreased the porosity of the films, hence, reduced the release rate, maximum released activities and the antimicrobial activities of the films. On the other hand, immobilized activities and the tensile strength of the films increased. The mechanical properties of the antimicrobial films cast with 5 % and 10 % CA were similar to those of lysozyme free CA films. However, significant reductions in tensile strength and elongation values were observed for the antimicrobial films prepared with 15 % CA. Differences in the release rates, soluble, immobilized and antimicrobial activities at porous and dense surfaces of the films suggest that different surfaces of CA films can be employed for antimicrobial packaging according to the targeted shelf-life of the food products. When the films made with 5 % CA were stored at 4 °C for a maximal period of 105 days, an increase in soluble lysozyme and antimicrobial activities of the films were observed. The results demonstrate that CA films prepared in this study show promising potential to achieve controlled release in antimicrobial packaging.Master Thesis Preparation and Characterization of Corn Zein Coated Polypropylene (pp) Films for Food Packaging Applications(Izmir Institute of Technology, 2007) Atik, İsa Doğan; Tıhmınlıoğlu, Funda; Tıhmınlıoğlu, Funda; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe plasticized corn-zein coatings on polypropylene (PP) films as an alternative to multilayer packaging films consisting of non-degradable polymers were prepared to evaluate barrier, mechanical, thermal, surface and optical properties of the resulting coated film, as affected by coating formulation (solvent, corn-zein, plasticizer concentration, and plasticizer type). PP films coated with corn zein were obtained through a simple solvent casting method. Corn-zein with different amounts (5% and 15%) was dissolved in 70% and 95% aqueous ethanol solution at 50oC, respectively. Solutions of corn-zein plasticized by polyethylene glycol (PEG) and glycerol (GLY) with various levels (20% and 50%) were applied on corona-discharged-treated PP film. The resulting corn-zein coated PP films showed good appearance, flexibility and adhesion between the coating and the base film. The coated PP films showed a significant (P<0.05) increase in barrier (water and oxygen) properties and improvement in mechanical properties when coating formulation consisted of higher corn-zein content and lower amount of GLY as plasticizer. Furthermore, zein coating increased the service temperature range of the PP films, and promised good printability on the surface due to contact angle results. The statistical analysis defined that the key parameters of coating formulation that had major effect on the final properties of coated PP films as corn-zein concentration, plasticizer concentration, and plasticizer type while ethanol concentration was found to be as less effective parameter compared to others. In conclusion, corn zein coatings with appropriate formulation on PP films could have potential as an alternative to conventional synthetic coatings for food packaging applications.