Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Publisher: search.filters.publisher.Izmir Institute of TechnologySubject: search.filters.subject.Mesoporous materials

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  • Master Thesis
    Numerical and Experimental Investigations on the Zeta Potential of Different Size Mesoporous Silica Nanoparticles With Different Porous Properties
    (Izmir Institute of Technology, 2020) Barışık, Murat; Barışık, Murat; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Mesoporous silica nanoparticles (MSN) are utilized by many applications due to their high surface to volume ratio, tunable pore size, low toxicology, and colloidal stability. These properties make silica nanoparticles good candidates for targeted drug delivery applications. Targeted drug delivery steps include cellular internalization, endosomal escape, and cargo release to the selective tissue. The geometric properties of MSN such as particle size, pore size, and porosity, as well as surface chemistry and resulting surface charge density determine the MSN behavior in these steps. This study examines the influence of particle size, pore size, and porosity of an MSN to its surface zeta potential. We performed both numerical and experimental investigations. The zeta potential of various MSNs at different salt concentrations was calculated by solving the Poisson-Nernst-Planck equation with active surface charge boundary conditions considering surface chemistry. We validated our multi-ion model through experiments. Results indicate that zeta potential exhibits a strong dependence on particle size, pore size, and porosity. By increasing porosity and/or pore size, the absolute average zeta potential decreased up to 25% from the theoretical predictions. Second, zeta potentials of silica particles at different sizes and surface areas were experimentally measured at different salt concentrations. Particles were systematically characterized by measuring particle size using Dynamic Light Scattering (DLS), analyzing chemical properties using Fourier-transform infrared spectroscopy (FTIR), measuring surface area using Brunauer– Emmett–Teller (BET) analysis, and imaging using Scanning Electron Microscopy (SEM). A well-dispersed solution in colloidal stability was obtained by systematically tuning corresponding parameters. The absolute average zeta potential was found to increase with a decrease in particle size, while zeta potential was found to decrease with a decrease in surface area at a constant particle diameter, similar to numerical calculations.
  • Master Thesis
    Selective Hydrogenation of Citral Over Mesoporous Ru/Tio2 Catalysts
    (Izmir Institute of Technology, 2013) Hassan, Hassanain Abbas; Yılmaz, Selahattin; Yılmaz, Selahattin; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    The liquid phase citral hydrogenation was investigated over Ru/SiO2, Ru/TiO2 and Ru/TiO2/SiO2 catalysts. TiO2/SiO2 supports were prepared by sol-gel deposition, impregnation and absorption methods. The effect of the supports and catalyst reduction temperature, 300 ï‚°C (LTR) and 450 ï‚°C (HTR) on citral conversion and selectivity to unsaturated alcohols were examined. A well-defined crystalline anatase phase was only observed on the support prepared by absorption method, TiO2/SiO2-ABS. A high dispersion and interaction of Ru were observed over TiO2 for Ru/TiO2. Ru/TiO2/SiO2-ABS also displayed similar properties but to a lower extent. Ru/TiO2/SiO2-ABS catalyst showed the highest citral conversion (57.7 %) at LTR among the different Ru/TiO2/SiO2 catalysts. Its selectivity to UA was also high (70.2 %). This was attributed to a better metal support interaction and dispersion obtained by this method. However, a selectivity of 62.6 % was obtained over Ru/TiO2. Activity of the catalysts was mostly observed to decrease as reduction temperature increased from 300 ï‚°C to 450 ï‚°C. Citral conversion decreased from 57.7 % to 42.3 % over Ru/TiO2/SiO2-ABS. However, selectivities to unsaturated alcohol (nerol and geraniol) over Ru/TiO2 and Ru/TiO2/SiO2 catalysts were increased at HTR, reaching about 80 %. This was suggested to be due to more interaction of TiO2 with the Ru (strong metal support interaction). There was no significant change in the selectivity to UA obtained at HTR for Ru/SiO2. This was related to the inert nature of SiO2.