Sürdürülebilir Yeşil Kampüs Koleksiyonu / Sustainable Green Campus Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7755

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Department: search.filters.department.Thesis (Master)--İzmir Institute of Technology, ChemistryLanguage: search.filters.language.en

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Now showing 1 - 7 of 7
  • Master Thesis
    Development of Chemometric Calibration Toolbox and Its Application for Determination of Slep Adulteration
    (Izmir Institute of Technology, 2018) Akkoç, Gün Deniz; Özdemir, Durmuş; Özdemir, Durmuş; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    A chemometric calibration toolbox, which contains Inverse Least Squares (ILS) regression, Principle Components Regression (PCR), Partial Least Squares Regression (PLSR), Genetic Inverse Least Squares (GILS) regression, and Ridge regression, was developed in MATLAB environment. During the development, multiple strategies to improve the calculation speed, namely vectorization and parallelization, were employed. Besides these programmatic strategies, efficient cross-validation (CV) procedures were implemented that are specifically tailored for parameter tuning of PCR and PLSR. For GILS, by constructing CV matrices in advance, the computational cost was further reduced. Additionally, a Graphical User Interface (GUI), which also includes baseline correction and variable range selection capabilities, was developed. For increased convenience, regardless of the chosen model, the toolbox returns a single vector of regression coefficients that accounts for centering and scaling of variables along with variable selection. Using the developed toolbox, quantitative determination of salep adulteration was carried out through chemometric calibration methods on Mid-IR data obtained from FTIRATR which is a fast and easy-to-use spectroscopic instrument. The main motivation was the lack of an established method for determination of adulteration of salep which can be quite common due to very high price of pure salep, despite the strict legal regulations. Using 365 samples covering a wide range of adulteration scenarios with 20 adulterants, calibration models were obtained and evaluated. Ensemble model, obtained by averaging GILS and Ridge, yielded the best RMSEP of 6.82 (w/w %). To cope with the unspecific adulterant problem, SIMCA was employed to provide an qualitative insight about the presence of such compounds.
  • Master Thesis
    Spectroscopic Determination of Vegetable Oiland Biodiesel in Petroleum Diesel Using Mulitivariate Calibration
    (Izmir Institute of Technology, 2008) Arıkan, Aysun; Özdemir, Durmuş; Özdemir, Durmuş; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    Due to the limited petroleum reserves and pollutant effect of petroleum fuels, the use of alternative fuels has became important in recent years. Diesel is one of the most used petroleum fuel, whose exhaust emissions composed of harmful particles, that pollutes the environment. In this sense, vegetable oils and their esters (biodiesel) are considered environmentally friendly fuels, which reduce hazardous impact of diesel emissions. However, using vegetable oils directly in diesel engines may cause some engine problems due to their high viscosity. The most commonly used way to reduce their viscosity is the converting into biodiesel. Because biodiesel production is expensive and time consuming, diesel may be illegally adulterated with vegetable oils before converting into biodiesel.Diesel may also adulterated with kerosene due to the large price differences. The main impact of this adulteration is increased emissions, which damage the environment. On the other hand, the addition of kerosene may also damage the engine. Because of these reasons, it is important to determine these adulterants illegally present in petroleum diesel. In this study, we have determined the adulteration of diesel with sunflower, canola oil, used frying oil, kerosene, and biodiesel by different molecular spectroscopic techniques combined to genetic inverse least squares (GILS). The results showed that the GILS method is suitable in the fast determination of diesel adulteration with vegetable oils, used frying oil, kerosene, and biodiesel when combined to NIR, FTIR-ATR, and molecular spectroscopic techniques.
  • Master Thesis
    Preconcentration of Heavy Metals in Environmental Samples by Biosorption and Determination by Atomic Spectrometry
    (Izmir Institute of Technology, 2007) Şeker, Ayşegül; Eroğlu, Ahmet Emin; Eroğlu, Ahmet Emin; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    In the assessment of environmental quality, one of the priorities must be given to the determination of heavy metals. In the present study, Spirulina platensis, a cyanobacteria (or blue-green alga) was suggested to be used as a biosorbent prior to the atomic spectrometric determination of Pb, Cd and Ni in some environmental samples. For this purpose, the parameters which might be effective on the biosorption were investigated such as pH, time, initial metal ion concentration, biosorbent amount, temperature, kinetics of sorption, repetitive reactivity and ionic competition. According to the sorption kinetics, results obeyed well the pseudo second-order model. Freundlich, Dubinin Radushkevich and Temkin isotherm models were applied in describing the equilibrium partition of the ions. Freundlich isotherm was applied to describe the design of a single-stage batch sorption system. Thermodynamic parameters (.G0, .H0 and .S0) were calculated and the sorption process was found to be largely driven towards the products and it had an endothermic nature. Faster adsorption kinetics was observed for Pb2+ ions in comparison to Cd2+ and Ni2+ ions. Based on kinetic modeling, the apparent activation energy, Ea, was calculated to be 44 kJmol-1, -16 kJmol-1 and 54 kJmol-1 for Pb2+, Cd2+and Ni2+, respectively. The measurements of the repetitive reusability of Spirulina platensis indicated a large capacity towards the three metal ions. Sorption activities in a three metal ion system were studied and at an initial metal concentration of 100.0 mgL-1, % Pb2+ was found to be still high (85%).However, it decreased to less than 20% for Cd2+ and Ni2+ indicating the relative selectivity of the biosorbent towards Pb2+. Finally, the use of Spirulina platensis, in its natural form or after be immobilized onto various matrices (alginate, silicate, carboxymethylcellulose and polysulfone) was planned for the separation of heavy metals from the sample matrix.
  • Master Thesis
    A Novel Sorbent (mcm-41 Immobilized With N-Methylglucamine) for Removal/Preconcentration of Boron From Waters. Synthesis, Characterization and Applications To Water Samples
    (Izmir Institute of Technology, 2005) Kaftan, Öznur; Eroğlu, Ahmet Emin; Eroğlu, Ahmet Emin; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    Determination of boron has become an important task in a variety of analytical applications because of the increasing use of boron compounds in various industrial fields. Its concentration is generally low in many samples and this necessitates either the use of very sensitive analytical techniques or the application of suitable preconcentration methods prior to instrumental determination.In the present study, a novel sorbent was prepared by the functionalization of an inorganic support material, MCM-41, with N-methylglucamine for the uptake of boron from aqueous solutions prior to its determination by ICP-OES. Characterization of the newly synthesized material was performed using elemental analysis, XRD, DRIFTS, and BET analysis. Sorption behavior of the novel sorbent for boron was also investigated and found to obey Freundlich and Dubinin-Radushkevich (D-R) isotherm models. The maximum amount of B (as H3BO3) that can be sorbed by the sorbent was calculated from the D-R isotherm and was found to be 0.8 mmol of B per gram of sorbent. The applicability of the new sorbent for the removal/preconcentration of boron from aqueous samples was examined by batch method. It was found that the sorbent can take up 85 % of boron in 5 minutes whereas quantitative sorption is obtained in 30 minutes. Any pH greater than 6 can be used for sorption. The desorption from the sorbent was carried out with 1.0 M HNO3. For method validation, spike recovery tests were performed at various concentration levels in different water types and were found to be between 85-95 and 75-90 percent for ultra pure water and geothermal water, respectively.
  • Master Thesis
    Preconcentration and Atomic Spectrometric Determination of Rare Earth Elements (rees) in Environmental Samples
    (Izmir Institute of Technology, 2004) Pasinli, Türker; Eroğlu, Ahmet Emin; Eroğlu, Ahmet Emin; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    Determination of rare earth elements (REEs) in environmental samples is usually performed by the plasma techniques, inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). Due to low concentrations of REEs and usually the presence of heavy matrix, an efficient separation and preconcentration technique is required prior to instrumental measurements in order to achieve accurate and reliable results. In this study, different types of zeolites (Clinoptilolite, Mordenite, Zeolite Y, Zeolite Beta), ion exchangers (Amberlite CG-120, Amberlite IR-120, Rexyn 101, Dowex 50W X18) and chelating resins (Muromac, Chelex 100, Amberlite IRC-718) were proposed as adsorbent materials for the preconcentration of REEs in environmental waters prior to their determination by ICP-OES. It was shown that REEs can be retained by these adsorbents quantitatively in a broad pH range (pH>4) and their desorptions from the adsorbents can be realized with acidic eluents. Of the sorbents investigated, clinoptilolite was chosen for the subsequent studies. Spike recovery tests were performed at various concentration levels in different water types including pure water, bottled drinking water, river water, sea water, and tap water, and were found to change between 85-90%.
  • Master Thesis
    Development of Inductively Coupled Plasma Spectroscopic Methods for the Determination of Metals in Beluga (delphinapterus Leucas) and Pygmy Sperm (kogia Breviceps) Whale Liver Samples
    (Izmir Institute of Technology, 2005) Parlayan, Filiz; Eanes, Ritchie C.; Eanes, Ritchie C.; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    Inductively couple plasma optical emission spectrometry (ICP-OES) is widely used to monitor elements in biological samples from marine organisms for ecological evaluations. Matrix effects (particularly those related to acid and salt type and concentrations) can present a barrier to the applicability of this instrumental method. To have a better understanding of these effects and to choose a suitable internal standard to correct for the signal variations, a procedure based on Principal Component Analysis (PCA) of the data from an axial-mode ICP-OES instrument with sequential detection was performed. Different from other published studies, it was found that ionic lines were more affected by matrix changes. Elements with high ionization energies and energy sums such as Cd and Zn showed a significant change for signal intensities and calculated concentrations due to the presence of acid, salt, and multielement matrix effects. It was observed that acid has a higher influence on the analyte signal as compared to the "salt-only" case. Furthermore, when several interfering elements were present in the sample, the matrix effect was either enhanced or reduced when compared with a solution containing only a single interfering element. Applicability of the proposed technique for the analysis of whale liver homogenate NIST certified material was investigated. The values of the corrected concentrations were in good agreement with the certified values, confirming the capabilities of the selected internal standards for compensation of matrix effects.
  • Master Thesis
    Synthesis, Characterization of Cdsxse1-X Quantum Dots and Evaluation of Their Real-Time Motions in Live Cells
    (Izmir Institute of Technology, 2011) Ünal, Gülçin; Özçelik, Serdar; Özçelik, Serdar; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    The use of quantum dots as fluorescent labels in bioimaging is the most intensively studied subject. The aim of this study is to elucidate locations of quantum dots and track their motions in real time through confocal microscopy and to evaluate influence of surface chemistry on diffusions of quantum dots in live cells. In this study, trioctylphosphine oxide (TOPO) capped CdSxSe1-x quantum dots were synthesized and then TOPO molecules were exchanged with 3-mercaptopropionic acid and N-acetyl-Lcysteine to make quantum dots water dispersible for cellular imaging. Human lung adenocarcinoma epithelial cells (A549) and human bronchial epithelial cells (BEAS-2B) were incubated 1 hour with CdSxSe1-x quantum dots with a concentration range of 1-10 g/mL. Localizations and real time motions of quantum dots were tracked by a spinning disc confocal microscope. The center of fluorescent spots of quantum dots was determined by 2D Gaussian fitting with a sub-pixel resolution (<100nm/pixel). The mean square displacements, diffusion coefficients and trajectories in which quantum dots made motions were analyzed by the software ImageJ with a plug in Spot Tracker. Confocal images showed that both MPA and NAC cappped quantum dots were observed in the cytoplasm of cells. Trajectories of quantum dots in cellular environment demonstrated that the quantum dots performed various types of motions in live cells. Unimodal, trimodal and multimodal distribution histograms of the diffusion coefficeints were obtained for different capping agents (MPA and NAC) and cell types (A549 and BEAS-2B). We conclude that the surface chemistry regulates the motion of the quantum dots in the cellular environment.