Master Degree / Yüksek Lisans Tezleri

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Department: search.filters.department.Thesis (Master)--İzmir Institute of Technology, ChemistryPublisher: search.filters.publisher.İzmir Institute of Technology

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Now showing 1 - 10 of 10
  • Master Thesis
    Development of a New Infrared Spectroscopic Method Based on Multivariate Calibration for the Determination of Aluminum and Magnesium Oxid Thickness on Aluminum Foil and Sheets Surfaces
    (İzmir Institute of Technology, 2016) Meşe, Ayten Ekin; Özdemir, Durmuş; Özdemir, Durmuş; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    Surface oxidation is a general problem for certain industrial applications such as coating and painting of the finished rolled products. A detailed understanding for the oxide growth mechanism as well as the development of a simple analytical method to measure this oxide thickness is very important in aluminum rolling industry and this study aims to develop a spectroscopic method to determine the oxide thicknesses on the surface of the aluminum by using multivariate calibration and infrared spectroscopy. Two main series of different aluminum alloys (3005 and 3003BZ) were selected in this study to develop a proposed methodology which is based on the combination of Fourier Transform Infrared Spectroscopy (FTIR) with Grazing Angle ATR accessory and chemometrics multivariate calibration techniques. In order to obtain oxide thickness values, X-ray Photoelectron Spectroscopy (XPS) was used and aluminum oxide (Al2O3) and magnesium oxide (MgO) thicknesses determinations were carried out by two different multivariate calibration models which are Genetic Inverse Least Squares (GILS) and Genetic Partial Least Squares (GPLS). These models were able to predict Al2O3 and MgO thicknesses using FTIR that is faster, easier and cheaper to operate as well as from XPS. The correlation coefficients of XPS reference oxide thickness values versus FTIR-GATR based GILS and GPLS predicted values were better than 0.919 in range of 0 to 25 nanometers for Al2O3 and 0 to 35 nm for MgO. These results suggest that grazing angle FTIR-ATR spectroscopy may offer a simple and nondestructive alternative for quick determination of oxide layer thickness.
  • Master Thesis
    Solid Phase Extraction of Ibuprofen in Waters With Molecularly Imprinted Polymers Prior To Hplc-Dad Determination
    (İzmir Institute of Technology, 2016) Ölçer, Yekta Arya; Eroğlu, Ahmet Emin; Eroğlu, Ahmet Emin; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    Endocrine disrupting compounds (EDCs) attract great attention worldwide due to their undesired effects on human health. Ibuprofen, an example of endocrine disrupters, is a nonsteroidal anti-inflammatory drug (NSAID). In this study, highly selective molecularly imprinted polymers (MIPs) with different morphologies (as monolith and microspherical beads) were synthesized by bulk and precipitation polymerization strategies. MIPs were prepared by using acetonitrile as porogen, methacrylic acid (MAA) as monomer, trimethylolpropane trimethacrylate (TRIM) as crosslinker and the analyte, ibuprofen, as the template. MIPs revealed higher affinity to the template molecule as compared with non-imprinted polymers (NIPs). The MIP prepared by precipitation polymerization was decided to be used as the primary solid phase extraction (SPE) sorbent due to its higher binding capacity towards ibuprofen compared to the MIP prepared by bulk polymerization. Selectivity of MIP to ibuprofen was examined in the presence of structurally related compounds. In this study, a molecular imprinting solid phase extraction (MISPE) methodology was proposed for determination of ibuprofen prior to HPLC-DAD analysis. For this purpose, critical experimental parameters of MISPE method were optimized and determined as follows; solution pH of 8.0, sorbent amount of 25.0 mg for 10.0 mL of 1.0 mgL-1 working solution, sorption time of 30 min and MeOH:H2O (acetic acid, pH 3.0) ratio of 80:20 as desorption solution. The accuracy of the proposed methodology was verified with spike recovery tests for tap and drinking waters and overall recovery was found as 97.4 (± 0.3) for n=3.
  • Master Thesis
    Fabrication of Thin Layer Polymer-Based Biointerphase for Biosensing Application
    (İzmir Institute of Technology, 2016) Yücel, Müge; Yıldız, Ümit Hakan; Yıldız, Ümit Hakan; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    This study aims to fabricate polymer-carbon nanotube composite as a bioelectronic interface for sensing volatile organic compounds (VOCs) in exhaled breath. Sensor platform is made of two layers i) polymeric membranes and ii) conducting layer. Poly(vinylidene fluoride) (PVDF), polystyrene (PS), and poly(methyl methacrylate) (PMMA) are selected as model polymers that are processed by electrospinning to utilize polymeric membranes. Multi-walled carbon nanotubes (MWCNTs) are used to fabricate conducting layer on top of PVDF, PS, PMMA polymer membranes. Aqueous solution of well-dispersed MWCNTs are obtained by several purification and filtration steps and conductivity of working MWCNT solution is adjusted about 120 μS/cm for whole study. This solution is further used to impregnate PVDF, PS, PMMA membrane. The PVDF-MWCNT, PS-MWCNT and PMMA-MWCNT sensor platforms are tested by electrochemical station that recording electrical resistivity change by time. All sensors platforms, made of three polymeric membranes-MWCNT, are found to be a responsive upon applying the toluene and acetone vapor. The sensing mechanism is hypothesized as the adsorption of VOCs onto the conducting CNT layer blocking electron stream on CNT network and causing resistivity change. The sensitivity of PVDF-MWCNT sensing platform is exceedingly higher with respect to other two candidates due to solvent vapor- polymeric membrane interactions. This contribution changes sensor platform characteristics and make them quite sensitive to trace amount of VOCs. Acetone and toluene are detected from ppm to ppb range and reproducible responses are recorded. As a result, acetone and toluene, biomarkers of diabetes and lung cancer, can be differentiated with produced sensor.
  • Master Thesis
    Copper-Catalyzed Synthesis of Benzo-Bimane Derivatives
    (İzmir Institute of Technology, 2016) Zeybek, Hüseyin; Emrullahoğlu, Mustafa; Emrullahoğlu, Mustafa; 04.04. Department of Photonics; 04. Faculty of Science; 01. Izmir Institute of Technology
    1,5-Diazabicyclo[3.3.0]octadienediones (shortly 9,10-dioxabimanes or "bimanes") are small heterocyclic structures which have important chemical, photochemical and photophysical properties. There are two existing structural isomers for bimane compounds ("syn" and "anti"). The syn-isomers have strong UV absorption properties and high quantum yields and are highly fluorescent. Bimane compounds are widely used for fluorescent labelling in biological systems because of their high photo-stability and bio-compatibility. Despite their unique properties, there is very few examples of study in literature. Because of synthetic difficulties of literature examples and their requirements such as hazardous chemicals, new methodologies are in high demand. In this study, new methods utilising metal catalysis for the effective synthesis of bimane compounds have been developed. Bimanes, which in the literature are synthesised with extreme difficulties and low yields, were synthesised in this work through simple and efficient protocols that employ metal, ligand and base. We further investigated the photophysical properties for all newly synthesized bimane derivatives. In the course of thesis study, a new and efficient method have been developed and optimised for the facile synthesis of benzo-bimane compound via the copper(I) catalyzed intramolecular C-N bond formation reaction. Moreover, with the aid of this new methodology, various analogues of benzo-bimane compound were synthesized in moderate to good yields under mild reaction conditions . Also, photophysical properties of benzo-bimanes were investigated carefully.
  • Master Thesis
    Production and Characterization of Water Soluble Cdsete Based Core/Shell Nanocrystals and Their Applications in Bioimaging
    (İzmir Institute of Technology, 2009) Özdemir, Seda; Özçelik, Serdar; Özçelik, Serdar; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    In recent years, nanotechnology has become one of the most intensively studied fields. At the nanometer scale, materials have unique electrical, optical, magnetic and chemical properties. They can be used for a wide variety of applications such as electrooptical devices, tagging and medical applications. The goal of this study was to produce water-dispersible alloyed CdSexTe1-x semiconductor nanocrystals, which are suitable to interact with biomolecules. CdSexTe1-x nanocrystals were synthesized by a single step aqueous synthesis method. Monodisperse, CdSexTe1-x nanocrystals with zinc blende structure were obtained in water. Synthesized nanocrystals emit in the range from 528 nm to 620 nm. CdSexTe1-x nanocrystals have 17% photoluminescence quantum yield, after the CdS shell coating the photoluminescence quantum yield increased up to 22%. MTT test and Trypan Blue tests were used to evaluate the toxicity of CdSexTe1-x nanocrystals. MTT measurements reveal that the MCF7 cancer cells are not affected by the nanocrystals at any dosage and exposure condition, but lethal effects are determined at the concentration of 1.0ug/ml for the PC3 cells. The BEAS 2B cells are very sensitive to the nanocrystals and do not proliferate at concentration of 0.5ug/ml. Confocal microscopy studies show that the nanocrystals has ability to penetrate to the cytoplasm of cells.
  • Master Thesis
    Multivariate Statistical Optimization of Enzyme Immobilization Onto Solid Matrix Using Central Composite Design
    (İzmir Institute of Technology, 2013) Arpakcı, Tuğba; Özdemir, Durmuş; Özdemir, Durmuş; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    In recent years, scientist have been used alternative technology in order to increase enzyme stability and also reduce the cost of production of enzyme. Immobilization methods have attracted the attention of scientists due to its advantages in comparison with soluble enzyme or other methods. Immobilization process can be affected by many factors for this reason it is important to optimize the effective factors in order to enhance success of this process. In preliminary studies, Bradford protein assay was used for determination of protein concentration. In order to increase sensitivity and accuracy of this assay, Bradford protein assay was combined with a multivariate calibration methods. Genetic Inverse Least Squares (GILS) and Partial Least Squares (PLS) were used for multivariate calibration. Calibration model was constructed for various concentration of Bovine Serum Albumin (BSA). Standard Error of Calibration (SEC) and Standard Error of Prediction (SEP) were calculated and results of multivariate calibration method were compared with univariate calibration methods and each other. In this study, the bovine serum albumin immobilization studies were carried out. The bovine serum albumin was immobilized on chitosan nanoparticles and effective factors such as chitosan concentration, immobilization time, pH and temperature were optimized by using central composite design (CCD). Central composite design is used to investigate interaction between these parameters and to find the optimum values of effective factors.
  • Master Thesis
    Development of Chromatographic and Moleculer Spetroscopic Multivariate Chemometric Models for the Geographical Classification of Olive Oils
    (İzmir Institute of Technology, 2013) Çelik, Deniz; Özdemir, Durmuş; Özdemir, Durmuş; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    Olive oil is a fat obtained from the olive (the fruit of Olea europaea; family Oleaceae), a traditional tree crop of the Mediterranean Basin. The oil is produced by grinding whole olives and extracting the oil by mechanical or chemical means. It is commonly used in cooking, cosmetics, pharmaceuticals, and soaps and as a fuel for traditional oil lamps. The classification of olive based on geographical origin is of great interest since the quality of olive oil depends on its chemical composition and geographical origin. In this study, it is aimed to develop classification models using elemental and molecular composition of olive oil samples via chromatographic method and molecular spectrometry. For this purpose, olive oil samples from diffirent regions of Turkey (Manisa and Bursa) were collected from producers and they were scanned with Fourier Transform Infrared spectrometer equiped with attenuated total reflectance (FTIR-ATR) accesory, and Gas Chromatography (GC), High Performance Liquid Chromatography (HPLC). Afterwards, any clustering of samples based on their regions was investigated using principal component analysis (PCA) and hierarchical cluster analysis (HCA). In conclusion, although molecular spectrometry is more advantageous for the classification of olive oil samples in the case of saving time, saving chemicals and ease of usage, chromatography gave better classification results based on geograpical origin compared to results obtained with molecular spectrometry.
  • Master Thesis
    Comparative Adsorption Studies of Heavy Metal Ions on Chitin and Chitosan Biopolymers
    (İzmir Institute of Technology, 2007) Keleşoğlu, Serkan; Polat, Hürriyet; Polat, Hürriyet; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    In this study comparative adsorption studies of heavy metal ions (Cu2+, Pb2+,Cd2+, Ni2+) on chitin and chitosan biopolymers were performed to investigate the uptake performances. For this purpose chitosan was prepared from chitin in controlled experimental conditions and then these biopolymers were characterized with Elemental Analysis, Viscosity, FT-IR, Potentiometric Titration, XRD, SEM, Zeta Potential,Particle Size Distribution and TGA/DTA measurements. Batch adsorption experiments were performed at eight different initial heavy metal ion concentrations (10, 25, 50, 100, 250, 500, 750, 1000 m/L), two different temperatures (298.15 K and 328.15 K), time period ranging from 5 minutes to 1 day and pH of solutions ranging from 1 to 7. The results indicated that the uptake performence of chitin and chitosan biopolymer significantly changed with pH, adsorbent dosage,concentration and temperature. In general, chitosan biopolymer demonstrated greater fixation abbility for heavy metal ions than chitin. However the fixation trend of heavy metal ions on chitin and chitosan biopolymers was the same (Cu2+ > Pb2+ > Cd2+ > Ni2+). Moreover Irwing-Williams Series support the dominancy of the binding mechanism for Cu2+, Cd2+ and Ni2+ ions on both biopolymers. Adsorption of heavy metal ions on both chitin and chitosan biopolymers followed pseudo second order kinetics with the rate constant indicating faster adsorption on chitin for Cu2+ and Pb2+ ions and faster adsorption on chitosan for Cd2+ and Ni2+ ions.Both of the Freundlich and Langmuir adsorption isotherms seem to adequately represent the adsorption data obtained in this study. The positive value of enthalpy change (Ho) and negative value of free energy change (Go) shows the adsorption process is endothermic and spontaneous. Moreover obtained positive entropy changes (So) show that an increase in randomness, is associating the adsorption of metal ions onto chitin and chitosan biopolymers.
  • Master Thesis
    Hydrothermal Synthesis of Solid State Materials and Crystallography
    (İzmir Institute of Technology, 2004) Özmen, Bahar; Emirdağ Eanes, Mehtap; Eanes, Mehtap; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    The structure solution of the new polyoxovanadate compound([V16O31(OH)7]Cl· 15H2O), has been done by the SHELX crystal solution software. The compound was synthesized solvothermally at 170 0C in the Northwestern University. The compound crystallizes in the space group C2/c of the monoclinic system with eight formula units in a cell of dimensions a = 18.070 (2) Å, b = 17.414 (2) Å, c = 15.1154 (18) Å, â= 97.696 (2)°, V= 4713.8 (10) Å3 (T = 153 K). The structure is composed of vanadium-oxygen clusters encapsulating Cl¯ anion. Each of the V centers has square pyramidal geometry coordinated by five O atoms. The 16 (VO5) units are fused together through common edges to form (V16O38) cage with Cl¯ anion in the middle. The single crystals of the [Ni(en)3(VO3)2] compound was synthesized by hydrothermal method. [Ni(en)3(VO3)2] compound is in the crystal system of hexagonal and in the space group P61. The unit cell parameters are a = 8.9940 (13) Å, b = 8.9940 (13) Å, c = 34.001 (7) Å and á = 90 0, â = 90 0, ã = 120 0. The structure is composed of VO4 tetrahedras which are joined with others by sharing corners into infinite chains running along the c axis. The complex cation [Ni(en)3]2+ are located between the chains The chain in the compound has a repetitive sequence of 12-nuclear corner-sharing tetrahedras. The compound was synthesized at 160 0C for 3 days in the steel reaction autoclaves which have PTFE (Polytetrafluoroethylene) cups in them.
  • Master Thesis
    Use of Amine-And Mercapto-Modified Silica as Soild Phase Extraction Sorbent for Speciation of Inorganic Selenium Prior To Determination by Atomic Spectrometric Techniques
    (İzmir Institute of Technology, 2010) Dönertaş, Esen; Eroğlu, Ahmet Emin; Eroğlu, Ahmet Emin; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    Silica-based sorbents containing amino-, mercapto-, and both functional groups (bifunctional) were prepared and used for the sorption of inorganic Se(IV) and Se(VI) species from waters prior to their determination by atomic spectrometric techniques, namely, inductively coupled plasma mass spectrometry (ICP-MS) and hydride generation atomic absorption spectrometry (HGAAS). The presence of the functional groups on the surface of the silica was demonstrated by using several characterization techniques such as scanning electron microscopy (SEM), solid-state NMR spectroscopy, thermo gravimetric analysis (TGA), elemental analysis and Brunauer-Emmett-Teller (BET) surface area analysis. Amine-modified silica was found to be selective towards Se(VI) at pHs 2.0 and 3.0 whereas mercapto-modified silica retains Se(IV) over a wide range from acidic regions to pH 4.0. Bifunctional silica, on the other hand, possesses the good features of the two sorbents; it can be used in the separate sorption of Se(IV) or of both Se(IV) and Se(VI) species. Acidic pHs (<1.0) are convenient for the sorption of Se(IV) alone where no sorption is observed for Se(VI). Alternatively, pH can be adjusted to 2.0 or 3.0 and Se(IV) and Se(VI) can be retained simultaneously. Desorption of selenium species from the sorbents was realized with two different eluents; 0.2% (m/v) KIO3 in 1 M HCl was used for Se(IV) and 2.0 M HCl for Se(VI). The efficiency of the proposed sorbents was demonstrated through spike recovery tests carried out with bottled drinking and tap water samples and the percentage recoveries were found to change between 82.2 ± 7.1 and 109.4 ± 3.6 for Se(IV). For Se(VI), mechanically mixed amino- and mercapto-modified (MIX) silicas in (1:1) ratio has shown the best performance with percentage recoveries of 87.1 ± 3.6 and 74.5 ± 6.6 for the spiked bottled drinking and tap water samples, respectively.