Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Design of Micelle Embedded Chitosan Nanocomposites for Targeted Delivery of Hydrophobic Drugs(Izmir Institute of Technology, 2016) Cihan, Esra; Polat, Hürriyet; Polat, Hürriyet; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyWhen successed to synthesize in a nanoparticulate form, chitosan has found to be a very effective biomaterial for drug delivery purposes owing to its extremely attractive characteristics such as its positive charge and pH sensitivity in aqueous medium. However, its structure as it is, is not suitable for oil soluble drugs. Even a close control on the size and shape of chitosan particles alone becomes a state of art and the production of chitosan nanoparticles is very difficult. Therefore, in this study, several methods were designed and used for synthesis of chitosan nanoparticles (<100 nm) with a hydrophobic core that are suitable for oil soluble drugs. Characterization of these nanoparticles were done by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), Scanning Transmission Microscope (STEM), Transmission Electron Microscope (TEM), surface tension and zeta potential measurements. It was concluded that the best method was the coupling of drug loading with simple ionic gelation method among all the others. Hydrophobic drug loaded micelle embedded chitosan nano particles were able to manufactured successfully. The sizes of chitosan particles that embed Pluronic-123 micelles were larger (<100 nm) than the sizes of Pluronic-123 micelles (20 nm) alone. It was also possible to obtain smaller chitosan nanoparticles (<50 nm) that embed drug loaded Pluronic-123 micelles when their structure is modified by Sodiumdodecylsulfate.Master Thesis An Investigation of Morphology of Polymeric Micellar Structures in the Presence of Protein for Drung Delivery Purposes(Izmir Institute of Technology, 2016) Kutluay, Gülistan; Polat, Hürriyet; Polat, Hürriyet; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyPolymeric micellar structures are becoming increasingly important in drug delivery applications. Morphology of these structures is a factor determining the form and the amount of the drug to be enveloped as well as how the release mechanisms will function. Though there are numerous work on micelles in the literature in aqueous media, understanding is lacking with respect to the specifics of the micelle formation and the exact morphology of the micelles produced within simulated body fluids (SBF) that also contains protein. In this work, the well-defined micellar structures with and without bovine serum albumin (BSA) in SBF using some selected polymeric surface active agents (PEO-PPO-PEO tri-block copolymer, P-123) were studied. The forms of P-123 molecules in distilled water (DW) and SBF (studied by surface tension measurements), micelle size distributions (studied by AFM, DLS, STEM, TEM), and electro kinetic potentials (studied by DLS) were the main parameters studied. DLS results showed that the average size of P-123 micelles did not change much in the presence of BSA in DW or SBF. In the cases of AFM, STEM and TEM, the sizes of P-123 micelles in the absence of BSA were comparable to the results of DLS. In the presence of BSA, on the other hand, the micelle structures come together to form large and loose aggregates in both DW and SBF. When P-123 micelles loaded with drug, DLS results showed that the presence of drug in micelles does not change the size of micelles much in both water and SBF. But STEM results show a considerable increase in the sizes of P-123 micelles. The drug loaded micelles seem to aggregate in water and SBF in the absence of BSA and in water in the presence of BSA. But they seem to disperse in SBF in the presence of BSA.Master Thesis An Investigation of Dye-Surfactant Intetactions in Aqueous Solutions for Elucidating the Mechanisms of Ultrafiltration(Izmir Institute of Technology, 2014) Olcay, Aybike Nil; Polat, Hürriyet; Polat, Mehmet; Polat, Mehmet; Polat, Hürriyet; 04.01. Department of Chemistry; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyLow Molecular Weight Contaminants (LMWCs) in waters are serious environmental concern due to removal problems with classical techniques such as chemical coagulation, biological treatments and adsorption. LMWCs are usually copresent with surface active agents in contaminated waters. Though such advanced removal techniques as ultrafiltration and micelle enhanced ultrafiltration are said to perform better, no systematic study is present for elucidating how the contaminantsurfactants interactions affect removal efficiency. In this study, methylene blue (MB), a dye widely employed in textile, paper and chemical industries, was chosen as the model contaminant. Surfactants selected were anionic sodium dodecyl sulfate (SDS), cationic hexadecyltrimethyl ammonium bromide (CTAB) and non-ionic ethoxylated octylphenol (TX-100). Surface tension, size, charge and contact angle measurements were conducted to investigate dye-surfactant interactions. Cellulose nitrate filters were employed to determine the effect of these interactions in filtration efficiency. It was found that significant amount of MB was removed from solution since it attached on the negatively charged cellulose nitrate filter. Though presence of surfactants generally decreased MB removal efficiency, MB-SDS interaction created large-loose aggregates at low SDS concentrations which cannot pass the filter paper. The MB-CTAB/TX-100 interactions created positively charged MB-surfactant pairs which can attach to the filter surface causing a decrease in the removal. At concentrations above Critical Micelle Concentration (CMC), the efficiency of MB removal is low due to the formation of surfactant-micelles that are smaller than the pores of the filter. Detailed size distribution experiments suggest that MB molecules are within the micelles structure, not in the core as believed in literature and do not increase the size of the micelle.Master Thesis Determination of the Particle Interactions -Rheology Suface Roughness Relationship for Dental Ceramics(Izmir Institute of Technology, 2007) Kes, Mürşide; Polat, Hürriyet; Polat, Hürriyet; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyIn this study, relationship between particle interactions, rheology and surface roughness for dental ceramics was determined. For this purpose IPS Empress 2 veneer powder was chosen and characterized with XRD, SEM, EDS, Zeta Potential and Particle Size measurements.Particle interactions have been interpreted in the light of DLVO Theory for distilled water and electrolyte solutions at different concentrations (0.1, 0.25, 0.5, 0.75,1 M NaCl and CaCl2). The results indicated that interactions between particles change with electrolyte concentration and valency. Electrical Double Layer Thickness (Debye Length) compresses and Energy Barrier height decreases as electrolyte concentration and valency increase mean that there is agglomeration between particles. In order to understand the rheological properties of the system shear rate versus shear stress and shear rate versus viscosity graphs were interpreted for the same environmental conditions, distilled water and electrolyte solutions at different concentrations. It was obtained that at low electrolyte conditions particles formed agglomerates, however at high electrolyte conditions the system reached equilibrium where particles formed gel structures due to their non-Newtonian behaviour.The results obtained from rheological measurements were compared with the results obtained from AFM, profilometer and SEM measurements for the surfaces prepared with IPS Empress 2 veneer powder and it was concluded that in the presence of electrolytes (Na+ and Ca2+) surface roughness increased at low concentrations due to agglomeration of particles whereas surface roughness decreased at high concentrations most probably due to gelation in the system. Moreover, this situation was supported with contact angle measurements where contact angle mean values are high and ditributions are wide at low electrolyte concentrations while contact angle mean values are small and distributions are narrow at high concentrationsMaster Thesis Characterization and Corrosion Performance of Γ-Glycidoxyropyltrimethoxsilane Modified Epoxy Polymer(Izmir Institute of Technology, 2010) Oturaklı, Şafak; Polat, Hürriyet; Polat, Hürriyet; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyEpoxy polymers have been widely used in a protective coating and adhesive due to its strong adhesion, high chemical resistance, and good processing characterisitics. However; epoxy coatings absorbs moisture easily, and the diffusion of absorbed water into the epoxy.steel interface weakens the interfacial adhesion strength between epoxy and steel in corrosive enviroment, due to the presence of hydrophilic hydroxy group in the cured network (epoxy/amine reaction). In this study, commercial epoxy polymer was chemically modified by γ-glycidoxypropyltrimethoxysilane monomer under the catalysis organotin compound via the reaction between hydroxyl group in epoxy polymer and alkoxy group in silanes, aiming to enhance the corrosion performans of epoxy polymer. Commercial epoxy polymer and silane modifed epoxy polymer were characterized by NMR spectroscopy, FTIR spectroscopy, epoxy equivalent weight measurement, contact angle measurement, surface energy measurement, hardness test and MEK double-rub test. The results showed that γ-glycidoxypropyltrimethoxysilane has been successfully grafted to epoxy polymer. Corrosion performance was evaluated by salt spray test acording to ASTM B117. The results showed that the chemically modified epoxy coating perform an improvement in resistance againts the penetration of water in polymeric resin and beter protectiveness on metalic corrosion.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 TechnologyIn 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 Removal of Phenol From Industrial Wastewaters Using Lignitic Coals(Izmir Institute of Technology, 2004) Molva, Murat; Polat, Hürriyet; Polat, Hürriyet; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyPhenol adsorption capacity of lignitic coals which were obtained from Soma and Yataan / Turkey was investigated under different operational conditions such as solid-liquid ratio (S/L), reaction time, initial phenol concentration and temperature. Based on batch adsorption studies, it was observed that the phenol was completely adsorbed by coal depending on time of adsorption and the S/L ratio. From these results, the maximum adsorption values on the time axis at various S/L ratios were used and the fractions of phenol receptive adsorption sites on coal surfaces were calculated as 60 % and 43 % for Soma and Yataan coals, respectively. Freundlich adsorption isotherm was found to describe the adsorption of phenol on lignitic coals well. The Langmuir model did not describe the system as good as Freundlich model most probably due to the monolayer coverage assumption on this model. Activation energy and the maximum heat of adsorption calculated using adsorption data at different temperatures by the Arrhenious and Van.t Hoff equations were 10.3 and -20.2 kJ/mol, respectively. The low energies suggest that the adsorption of phenol on these lignitic coals were through physical interactions. An adsorption mechanism of phenol on lignite was discussed based on these findings. Residual water quality following adsorption in terms of major elements and heavy metals was within acceptable limits defined for wastewaters. The amount of organic matters dissolved from coals were also negligable. The presence of heavy metals as Cu, Zn etc. in water as a contaminant was also found to affect the removal of phenol by about 10-20 %.Master Thesis Removal of Heavy Metals From Wastewaters by Ion Flotation(Izmir Institute of Technology, 2005) Erdoğan, Demet; Polat, Hürriyet; Polat, Hürriyet; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyIn this study, ion flotation experiments were performed to investigate the removal of heavy metals (copper, zinc, silver and chromium) from wastewaters.Various parameters such as pH, surfactant and frother concentrations and airflow rate values were tested to determine the optimum flotation conditions. Sodium dodecyl sulfate and Hexadecyltrimethyl ammonium bromide were used as collectors. Ethanol /MIBC were used as frothers.For 10 mg/L initial concentrations of copper, zinc, silver and chromium (III), the highest recoveries obtained were 90%, 71%, 73% and 97%, respectively. When the initial concentration of metals increased the recovery decreased. This proves the attachment of metal ions on surfactant molecules.The presence of Na+, Mg2+, Ca2+ ions in solution reduced the recoveries in case of all the metals since the presence of excess Na, Mg, Ca ions compete with metals and the metal ions can not find enough surfactant molecules to attach to.Selective flotation experiments were conducted in the presence of metal ion mixture solutions. It was possible to separate copper and chromium from zinc and silver, and also possible to separate chromium from zinc and copper and zinc from copper and chromium under suitable conditions.The classical first order equation fitted the results on flotation. Zinc and chromium floated not only more in an amount but also floated faster than copper.Surface tension measurements were conducted to investigate both the collector surfactants and the frothers at air/water interface since air bubbles carry the surfactant-metal ion complexes to the froth and separate from solution.Master Thesis Removal of Boron From Waters Using Fly Ash(Izmir Institute of Technology, 2005) Sütçü, Leman; Polat, Hürriyet; Polat, Hürriyet; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyIn this study, various operational parameters were tested in order to determine the feasibility of using fly ash to remove boron from aqueous solutions. Studied parameters include time of reaction, material type, solid-liquid ratio, temperature and boron concentration. Preliminary studies revealed that the ability of Yeniköy fly ash to remove boron is similar to that achieved by amberlite under certain conditions. Therefore, Yeniköy ash was selected for sorption studies which aimed at elucidating some of the thermodynamic and kinetic profiles of the sorption process. Experiments were performed using the batch technique at six different initial boron concentrations (10, 30, 50, 100, 250, 500 mg/L), three different temperatures (298, 308, 318 K) and time period ranging from 2 minutes up to 48 hours. The experimental results revealed that the percentage sorption of boron on Yeniköy fly ash can reach up to 100% under appropriate conditions. Results showed that sorption of boron on Yeniköy fly ash followed pseudo-second-order kinetics. The activation energies Ea, were obtained as -90.3, -57.8 and -6.1 kJ/mole for the initial concentrations of 10, 30 and 50 mg/L, respectively. Negative .Ho values were obtained for lower initial concentrations of boron (10, 30, 50 mg/L) indicating that the processes are exothermic. On the contrary, at high concentrations, positive .Ho values were obtained for boron sorption on fly ash indicating that the uptake process becomes endothermic. The entropy change of the sorption process was found in the range of (-234)-(158) J/mole-K.Master Thesis Kinetics of Oil Dispersion in the Presence of Chitosan Based Biopolymers(Izmir Institute of Technology, 2009) Şen, Didem; Polat, Hürriyet; Polat, Hürriyet; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyThis study was focused on the modification of chitosan to produce surface active biopolymers and their application as emulsifiers. Therefore N-acylation of chitosan was utilized. Characterization of the produced materials were achieved by the following ways; Ninhydrin assay, Elemental Analysis, Fourier Transform Infrared Spektroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), surface (or interfacial) tension and contact angle measurements. These characterizations provided information about the substitution degree, structure and the hydrophobic-hydrophilic properties of the produced surface active biopolymer. For example, the surface tension values were determined as decreasing from 71 mN/m to 40-50 mN/m in the presence of chitosan based bio-polymers with the substitution degrees between 25% and 45%. On the other hand contact angle values increased significantly in the case of chitosan based biopolymers. modifications with different initial mol ratios. The effect of these modified materials on the kinetics of oil emulsification was tested conducting in-situ size measurement studies and using a phenomenological dispersion model for the evaluation of data. This way the dispersion rate constants were able to calculated and used to compare the different conditions used to prepare emulsions. As a conclusion, the coalescence sub process that becomes dominant after 8 minutes of emulsification (in the case of oil only) totally disappeared in the presence of both chitosan and N-acylated chitosan. The rate of oil dispersion up to 8 minutes, however, did not change much in all the cases. The effect of modified chitosan on the kinetics was not significant. These were postulated as the possible changes in the configurations of the modified chitosan molecules due to the increased hydrophobic character and inter molecule interactions.