Master Degree / Yüksek Lisans Tezleri

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

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Department: search.filters.department.Thesis (Master)--İzmir Institute of Technology, Chemical EngineeringSubject: search.filters.subject.Membranes (Technology)

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Now showing 1 - 5 of 5
  • Master Thesis
    Modification of polysulfone ultrafiltration membranes with polydopamine deposition and dextran grafting for enhanced whey protein filtration
    (01. Izmir Institute of Technology, 2024) Alsoy Altınkaya, Sacide; Altınkaya, Sacide; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Bu çalışmada, 10 kDa ve 100 kDa ticari polisülfon (PSF) membranların protein kirlenme direncini artırmak için iki farklı yüzey modifikasyon yöntemi geliştirilmiştir. İlk yöntemde, oksijen gaz akışı altında ve klasik polimerizasyon yaklaşımı kullanılarak dopamin kaplama yapılmıştır. 1 g/L peynir altı suyu çözeltisi ön işlemden geçirildikten sonra dopaminle modifiye edilmiş membranlardan süzülmüştür. Oksijen gaz akışı altında 10 dakikada dopamin ile kaplanan 10 kDa PSF membranı %18'lik bir akı düşüşü ve en yüksek akı geri kazanım oranı (%86) ile minimum kirlenme göstermiştir. Öte yandan, benzer koşullarda dopaminle kaplanan 100 kDa PSF membranı kaplanmamış haline göre daha fazla kirlenmiştir. Klasik yöntemle kaplanan dopamin her 2 PSF membranında kirlenme dirençlerini iyileştirememiştir. Tezde uygulanan ikinci yöntemde, PSF membranları farklı dekstran konsantrasyonları kullanılarak ve farklı kaplama sürelerinde dekstran aşılama ile modifiye edilmiştir. Bu membranlardan peynir altı suyu ön işlemden geçirilmeden filtrelenmiştir ve 20 mg/mL dekstran konsantrasyonu ile 2 saatlik bir aşılama süresi optimum aşılama koşulları olarak belirlenmiştir. Bu koşullar altında, 10 kDa membran %16,6 akı azalması ve %55,2 akı geri kazanım oranı, 100 kDa membran ise %55,9 akı azalması ve %91,3 akı geri kazanım oranı göstermiştir. 100 kDa ve 10 kDa dekstran aşılı membranların seri bağlanması durumunda en yüksek protein konsantrasyon faktörü (10) elde edilmiş, bu konfigürasyon 10 kDa aşılı membranın akı geri kazanım oranını %55'ten %83'e çıkarmıştır. Tüm membranlar SEM-EDX, zeta potansiyeli, AFM, TGA, XPS, FTIR-ATR, yüzey serbest enerjisi ve temas açısı ölçümleri kullanılarak karakterize edilmiştir. Dekstran aşılanmış ve PDA kaplanmış membranların alkali ortamlarda stabil olmadığı görülmüştür.
  • Master Thesis
    Development of a Novel Low-Pressure Nanofiltration Membrane for Li+ Mg2+ Separation
    (2023) Alsoy Altınkaya, Sacide; Altınkaya, Sacide Alsoy; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Lithium-based batteries stand out as a crucial technology for energy storage. Between 2020 and 2022, lithium production surged from 77,000 to 100,000 tons. The majority of the world's lithium reserves are situated in water resources. Nevertheless, the direct extraction of lithium requires additional chemical processes due to the presence of other salts. Nanofiltration is recommended as an environmentally friendly and economical method for lithium purification. The main objective of this thesis is to develop a nanofiltration membrane for efficient Li+ and Mg2+ separation. The support membrane was prepared through the phase inversion technique using polyamide-imide (PAI) in the casting solution and polyethyleneimine in the coagulation bath. In-situ dopamine polymerization under oxygen backflow formed an intermediate layer on the support surface for further modification. PDA-modified support was first coated with polyethyleneimine (PEI) functionalized alumina particles and then low molecular weight PEI (800Da). The final membrane design was optimized for Li+ purity and Li+ recovery. The produced nanofiltration membrane exhibited significant rejection rates, notably around ~90% % for Mg2+ and approximately ~ -21% for Li+. Additionally, it demonstrated a pure water permeability of 9.7 L/m2hbar. Each membrane layer underwent characterization through various techniques, including SEM, EDX, zeta potential analysis, AFM, and contact angle measurements. The membrane was subjected to stability tests under dynamic and static conditions. Li+ and Mg+2 rejections, separation factor, and salt solution flux did not change after 30 days of storage in 2000 ppm salt solution and during 72 h dynamic filtration test.
  • 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
    Measurement and Modeling of Thermodynamic and Kinetic Data of Membrane Forming Systems
    (Izmir Institute of Technology, 2007) Arslan, Mine Özge; Alsoy Altınkaya, Sacide; Alsoy Altınkaya, Sacide; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Phase inversion process involving a ternary system (nonsolvent/solvent/ polymer) isfrequently used to prepare porous and asymmetric polymeric membranes. The thermodynamic and kinetic data for the ternary system are required to understand membrane formation mechanisms, change the preparation conditions and predict the final structure of the membranes. In this study, cloud point curves for polysulfone (PSf)/1-methyl-2-pyrrolidinone (NMP)/water, PSf/tetrahydrofurane (THF)/water, PSf/NMP/ethanol, PSf/THF/ethanol, polymethyl methacrylate (PMMA)/acetone/water, PMMA/ THF/water, PMMA/acetone/formamide and PMMA/THF/formamide systems were measured by titrating polymer solutions with nonsolvents until the onset of turbidity.Binodal curves were calculated by using the Flory Huggins theory with constant interactionparameters. Theoretical ternary phase diagrams were found to be in good agreement with experimental cloud point data. In addition to liquid liquid equilibrium data, sorptionisotherms and diffusion coefficients of water, ethanol and chloroform were measured byusing a magnetic suspension balance. Results of kinetic studies have shown that water sorption in PSf films exhibits Fickian diffusion while anomalous diffusion is observed for ethanol and chloroform sorption. The kinetic data for water sorption was analyzed using a simple Fickian diffusion model to determine the diffusion coefficients. On the other hand, anamalous sorption kinetics were interpreted by a mathematical model involving independent contributions from Fickian diffusion and polymer relaxations. The model successfully fits non-Fickian anomalies including sorption overshoot and allows to determine diffusion coefficients and relaxation times. Diffusivities of penetrants in PSf was found to decrease in the following order: Water > Chloroform > Ethanol. Equilibrium sorption isotherms of ethanol and chloroform are well described by classical Flory Huggins thermodynamic theory with constant interaction parameters. A modified version of this theory for concentration dependent interaction parameter is used to correlate the sorption isotherm of water. Vrentas Duda free volume theory is able to correlate diffusivity data of water collected at 30 C and 40 C while the theory fails to correlate the diffusivities of ethanol and chloroform both of which were determined from diffusion-relaxation model.
  • Master Thesis
    Preparation and Characterization of Hemodialysis Membranes
    (Izmir Institute of Technology, 2007) Yaşar Mahlıçlı, Filiz; Alsoy Altınkaya, Sacide; Alsoy Altınkaya, Sacide; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Hemodialysis is a widely used clinical therapy for end-stage renal failure and dialysis membranes are vital components of a hemodialysis unit. The most desirable properties of a hemodialysis membrane are high mass transfer of toxic solutes to reduce the dialysis time, blood compatibility and limited protein adsorption capacity. Protein adsorption or deposition on the surface or in its pores results in a progressive decline in flux, change of selectivity of the membrane and the activation of different defense systems in blood. To prepare hemodialysis membranes with improved transport properties and protein adsorption resistant surfaces, an enzyme immobilization technique was used. Asymmetric cellulose acetate membranes were prepared through dry phase inversion method and they were modified by blending urease enzyme directly into the casting solution. The effect of enzyme immobilization on the protein adsorption, solute transport rates and mechanical properties was investigated through static adsorption and permeation experiments, mechanical tests and structural characterization by scanning electron microscope. It was found that the solute permeation rates decreased exponentially while the maximum tensile strength of the membranes increased significantly by increasing the cellulose acetate (CA) to acetone weight fraction ratio in the membrane forming solution due to a change in the structure from porous to dense one. Modification of the CA membrane with urease immobilization increased the permeation coefficients of creatinine and uric acid by a factor of 1.2 and 1.7, respectively. Similarly, the % removal of urea from the donor compartment in 1 hour increased from 45.8% to 53.2% by using urease immobilized CA membrane. The protein adsorption capacity of the urease immobilized CA membrane was found to be 2 times lower than that of the regular CA membrane. Protein fouling on the membranes caused a decrease in the transport rates of all solutes. Due to protein fouling, the decrease in the permeation coefficients of creatinine and uric acid are 59.0% and 76.5%, respectively, through regular CA membranes. On the other hand, urease immobilization limited the decrease in the permeation rates by 39.2% and 33.4% for creatinine and uric acid, respectively. In a similar way, the rate of removal of urea through CA membrane and urease immobilized CA membrane decreased by 31.2% and 11.7%, respectively. While urease immobilization decreased the protein adsorption capacity, it did not cause any loss in mechanical strength of the membrane. These results indicate that urease immobilization can be used to improve transport properties and reduce protein adsorption capacity of the CA membranes. Urease immobilized CA membranes prepared in this study can be used as an alternative membrane in hemodialysis units.