Master Degree / Yüksek Lisans Tezleri

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

Browse

Filters

2007 - 200912010 - 20172

Settings

Author: search.filters.author.Alsoy Altınkaya, SacideSubject: search.filters.subject.Thin films

Search Results

Now showing 1 - 3 of 3
  • Master Thesis
    Development of Nanofiltration Membranes Through Surface Modification of Polysulfone Based Ultrafiltration Membranes
    (Izmir Institute of Technology, 2017) Bar, Canbike; Alsoy Altınkaya, Sacide; Alsoy Altınkaya, Sacide; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Stimuli responsive membranes have been used for suppressing fouling and regulating selectivity in different applications. These types of membranes are usually manufactured in thin film composite structure by either polymerizing stimuli-responsive monomer or coating stimuli-responsive polymer on a support. Responsiveness is due to their characteristic features which rely on reversible changes in mass transfer and interfacial properties as a result of changes in external environment such as pH, temperature and ionic strength. In this study, a pentablock copolymer (PBC) which consists of temperature responsive Pluronic F127 (PEO-b-PPO-b-PEO) in the middle block and pH responsive poly(N,N-(diethylamino)ethyl methacrylate) (PDEAEM) in the end blocks was used for designing a new type of thin film composite (TFC) nanofiltration membrane. The support of the composite membrane was prepared from a blend of polysulfone/sulfonated polyethersulfone using nonsolvent induced phase separation and the PBC was attached to the support via electrostatic interaction. The conformation of grafted PBC chains was determined by adsorption studies. The effects of PDEAEM block length, concentration of the copolymer and adsorption time on the adsorbed amount were investigated. Among three copolymer samples investigated (15, 20 and 25 kDa), the 25 kDa PBC displayed the highest responsiveness, thus, rejection properties were determined for the membranes prepared only from this sample. The influences of operation pH and temperature on the structure integrity of the membrane were investigated with pure water permeability measurements and the change in pore size was assessed by determining rejection of neutral solutes by the membranes. The membranes were further characterized with SEM, AFM, contact angle, XPS and zeta potential measurements. It was demonstrated that a new pH and temperature responsive, high flux TFC NF membrane was manufactured.
  • Master Thesis
    Development of Thin Film Composite Nanofiltration Membranes With Layer by Layer Polyelectrolyte Deposition
    (Izmir Institute of Technology, 2017) Tekinalp, Önder; Alsoy Altınkaya, Sacide; Alsoy Altınkaya, Sacide; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Nanofiltration (NF) membranes are usually prepared in thin film composite (TFC) structure through polymerization of various monomers or coating of previously synthesized polymer on porous support membranes. Layer by layer (LbL) deposition of polyelectrolytes on a porous support is a facile and convenient method for the sake of producing NF membranes. This study intends to manufacture TFC NF membrane via alternating polyelectrolyte deposition with limited number of layers on polysulfone/sulfonated polyethersulfone (PSF/SPES) porous support membrane. Polyethyleneimine (PEI) and alginate (ALG) were chosen as polyelectrolyte pairs. The support membranes with different pore sizes were prepared via nonsolvent induced phase inversion method by changing compositions and thickness of casting solution as well as composition of coagulation bath. The polyelectrolytes were deposited dynamically in a dead end filtration module at 1 bar. The influences of supporting electrolyte, polyelectrolyte pH and concentration as well as type of coating method on the membrane performances were investigated. The membranes were characterized by SEM, AFM, staining, and contact angle measurements. Stability and fouling tendency of produced membranes were determined. It was demonstrated that NF membrane (83% PEG1000 rejection) with a high flux (14 L/m2.h.bar) can be manufactured by depositing only a single layer of PEI. Further deposition of ALG on PEI-coated membrane resulted in water permeability of 15.5±0.3 L/m2.h.bar with 89.1±0.6% PEG1000 rejection by adjusting PSF:SPES ratio to 4:1.
  • Master Thesis
    Preparation and Characterization of Antimicrobial Polymeric Films for Food Packaging Applications
    (Izmir Institute of Technology, 2007) Gemili, Seyhun; Alsoy Altınkaya, Sacide; Alsoy Altınkaya, Sacide; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    In this study, cellulose acetate (CA) based antimicrobial packaging materials containing lysozyme as an antimicrobial additive were developed. In order to achieve appropriate controlled release of antimicrobial agent, the structure of the films were changed from highly asymmetric and porous to dense ones by modulating the composition of the initial casting solution. The effectiveness of the films were then tested through measurement of soluble and immobilized lysozyme activity, release kinetics and antimicrobial activity on selected microorganisms. The highest release rate, soluble lysozyme activity and resulting antimicrobial activity (on E.coli) was obtained with the film prepared from 5 % CA solution including 1.5 % lysozyme. Increasing CA content in the casting solution decreased the porosity of the films, hence, reduced the release rate, maximum released activities and the antimicrobial activities of the films. On the other hand, immobilized activities and the tensile strength of the films increased. The mechanical properties of the antimicrobial films cast with 5 % and 10 % CA were similar to those of lysozyme free CA films. However, significant reductions in tensile strength and elongation values were observed for the antimicrobial films prepared with 15 % CA. Differences in the release rates, soluble, immobilized and antimicrobial activities at porous and dense surfaces of the films suggest that different surfaces of CA films can be employed for antimicrobial packaging according to the targeted shelf-life of the food products. When the films made with 5 % CA were stored at 4 °C for a maximal period of 105 days, an increase in soluble lysozyme and antimicrobial activities of the films were observed. The results demonstrate that CA films prepared in this study show promising potential to achieve controlled release in antimicrobial packaging.