Master Degree / Yüksek Lisans Tezleri

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

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Access Right: Embargoed AccessAuthor: search.filters.author.Ebil, Özgenç

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  • Master Thesis
    Recovery of Lithium From Aqueous System Using Manganese Oxide Adsorbent With Developed Electrospun Mat Substrate
    (01. Izmir Institute of Technology, 2023) Akgün, Berk; Ebil, Özgenç; Demir, Mustafa Muammer
    Lithium is used in many fields due to its high energy density and unique electrochemical properties. Recently, there has been a strong increase in demand for lithium, so the extraction of lithium from natural water resources has become a remarkable research topic. One of the most effective methods of separating lithium from natural water sources is adsorption using lithium ion-sieve adsorbents. However, the powdered nature of the adsorbents makes them challenging to process and less recyclable. Recent studies have focused on developing adsorbents using different polymeric materials as substrates or binders. In the thesis, as a new approach, flexible and free-standing polyurethane electrospun mat substrates were produced and combined with λ-MnO2 to extract lithium from aqueous systems, and their lithium removal performance was investigated. After the fabricated mats and λ-MnO2 powder were characterized, the deposition process was performed, and filtration studies were carried out in synthetic lithium solution. Optimum conditions for lithium removal were found as an adsorbent amount of 200 mg, and 200 ppm initial [Li+], and pH 12. In addition, lithium removal performances have been improved by stacking mats and multi-stage filtration processes. Lithium removal reached 76.6% when a 400 ppm lithium solution and an 8-step filtration were used. Lithium removal experiments were performed with salt-lake brine containing high concentrations of various ions and showed that these ions reduced the lithium removal. In the study, PU electrospun mats for λ-MnO2 powder were found to be a promising substrate for lithium removal from aqueous systems.
  • Master Thesis
    Development of protective nano-coatings for electro-optical systems
    (01. Izmir Institute of Technology, 2016) Karabıyık, Merve; Ebil, Özgenç
    Electro-optical (EO) systems have wide range of applications and in recent years, especially the use of EO imaging systems in military and civil aviation applications have substantially increased. In these applications, EO systems are exposed to quite harsh and unstable operating conditions like sudden changes in temperature and humidity, dust, fog, physical shock, vibration and radiation. If their optical surfaces such as prisms, lenses and mirrors are damaged due to these conditions, their repair usually is not possible. To overcome these problems, it is necessary to develop special protective coating layers for optical surfaces. The main goal of this study is to produce protective, self-cleaning and super-hydrophobic polymeric thin films for optical surfaces of the electro-optical (EO) systems. Initiated chemical vapor deposition (iCVD) is a novel method for the fabrication of thin film coatings and it has many advantages such as low production cost, very low deposition temperature, 3D geometry coating performance and high deposition rate. Therefore, iCVD was employed to fabricate homopolymers of poly (glycidyl methacrylate) (PGMA) and poly (1H, 1H, 2H, 2H-Perfluorodecyl acrylate) (PPFDA) and P(GMA-PFDA) copolymer thin-films as protective coatings for EO systems. Optical modeling and simulations were performed to determine the effect of film thickness and refractive index on optical performance of substrates to be coated. Optical performance of fabricated coatings was also measured between 400 and 1000 nm range to confirm that protective coatings do not have any measureable impact on optical performance provided that the protective film thickness is kept between 50 nm to 1 μm. The surface morphology of the protective coatings was evaluated using a variety of analytical tools such as Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Contact Angle measurements. Optical tests were performed by following MIL-F-48616 Military Standard (MIL-STD). The best protective coatings were obtained by using P(GMA-PFDA) copolymer which yields good mechanical properties due to epoxy pendant group and super hydrophobicity due to incorporation of fluoro monomer.