Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Manufacturing of Starch-Based Bioplastic From Waste Potato Starch by Extrusion and Energy Analysis of the Production(2023) Tıhmınlıoğlu, Funda; Gökyıldız, Yasemin; Alsoy Altınkaya, Sacide; Altınkaya, Sacide; Tıhmınlıoğlu, FundaPlastic materials are an essential part of our daily lives and annual plastic production is higher than 380 million tons with a 4% annual increasing rate. Since the 1950s, 8.3 billion tons of plastic have been produced, 9% of these plastics have been recycled, 12% have been incinerated and the rest 79% have been dumped to landfills. Therefore, the development of biodegradable polymers obtained from renewable raw materials has become a priority to reduce the environmental impact and dependency on fossil resources. Thermoplastic starch (TPS) is a starch-based bioplastic obtained by the disruption of the starch granules with thermal and mechanical forces in the presence of plasticizer. In this thesis, production of TPS from residual potato starch by extrusion was investigated. The extrusion trials were conducted in a single-screw extruder. Glycerol was selected as plasticizer and added to starch with 20, 30 and 40 wt.%. Extrusion temperature profiles were 50-90oC, 60-90oC and 70-90oC. The pretreatment conditions for the residual starch were drying to 10 wt.% moisture content and sieving with 131μm mesh size. Specific mechanical energy values ranged between 7.89 kWhkg-1 and 43.27 kWhkg-1. The optimum product formation was selected according to processability with lower energy consumption and mechanical properties as TPS303 which has 30 wt.% glycerol content and processed between 70-90oC. Specific mechanical energy consumption for TPS303 was found to be 23.78 kWhkg-1. The mechanical properties of TPS303 were 4.48 MPa tensile strength, 59.74 MPa Young's modulus and 57.33% elongation at break. Consequently, residual potato starch was found to be a promising raw material for thermoplastic starch production with proper pretreatment.Master Thesis Development of Polyamideimide Based Nanofiltration Membranes for Separation of Dyes and Salts in Textile Wastewater Treatment(Izmir Institute of Technology, 2019) Metecan, Ayşe; Alsoy Altınkaya, SacideThe textile wastewater contains a significant level of organic dyes and inorganic salts. Separation of a vast amount of organic dyes and inorganic salts is important not only to comply with strict regulations but also to recover dyes for reuse during the process. Nanofiltration is proposed as a cost-effective alternative solution for dye and salt separation compared to traditional techniques. The main objective of this thesis is to develop a polyamideimide based positively charged nanofiltration membranes with high permeability, and high selectivity for separation of dyes and salts in textile wastewater treatment. Polyamide-imide (PAI) is an excellent choice for membrane production because of its superior processability, good mechanical features, and high chemical and thermal resistance. Its imide groups are crosslinked with polyethyleneimine (PEI), which is a suitable material to obtain a positively charged surface. In this study, support membranes of various pore sizes were produced by changing the composition of the coagulation bath and casting solution during the phase inversion method. Then, the optimum support membrane was in-situ modified with the alginate and coordinated with the metal ions for high permeability and high selectivity. The influences of the metal concentration and reaction time on the membrane performances were examined. It has been demonstrated that resulted nanofiltration membrane has high solute permeability (>22 L / m2 h bar), high dye rejection (~ 95 %) and low salt rejection (~ 11 %). Moreover, this membrane was tested in the treatment of real textile wastewater samples. Salts in wastewater permeated, while high amounts of dye were rejected.Master Thesis Preparation and Characterization of Antifouling Nanofiltration Membranes From a Responsive Pentablock Copolymer(Izmir Institute of Technology, 2018) Çağlar, Nağahan; Alsoy Altınkaya, SacideThe most substantial factor restricting the extensive application of membrane processes is the fouling problem resulting from the deposition of solutes in water on the surface or within the pores of membranes. The frequently used chemical washing procedure to eliminate the fouling issue causes environmental pollution and shortens the membrane life. In order to overcome these disadvantages, the development of membranes possessing low fouling potential is needed. In recent years, the stimuliresponsive polymers have received attention for developing membranes possessing low fouling potential. The antifouling property of these membranes is controlled through the change in their conformation and hydrophilic/hydrophobic characteristics as a response to change in external stimuli such as pH, temperature and ionic strength. The aim of this study was to design antifouling nanofiltration membranes (NF) using a pentablock copolymer 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. Effects of pH and temperature responsiveness on the membrane fouling were investigated. Fouling tendencies of the membranes were evaluated by using Bovine Serum Albumin (BSA), Alginate (ALG) as organic foulant and Escherichia coli (E.coli) as biological foulant. NF membranes were characterized by scanning electron microscope (SEM), contact angle and zeta potential measurements. It was demonstrated that pentablock copolymer coated membranes displayed antifouling resistance by changing filtration pH and temperature.Master Thesis Development of Nanofiltration Membranes Through Surface Modification of Polysulfone Based Ultrafiltration Membranes(Izmir Institute of Technology, 2017) Bar, Canbike; Alsoy Altınkaya, SacideStimuli 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, SacideNanofiltration (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 Development of Whey Protein Isolate Based Nanocomposite Food Packaging Film Incorporated With Chitosan and Zein Nanoparticles(Izmir Institute of Technology, 2014) Oymacı, Pelin; Alsoy Altınkaya, Sacide; Demir, Mustafa MuammerThe purpose of this study was to investigate the effect of chitosan and zein nanoparticles addition on the barrier and mechanical properties of whey protein isolate (WPI) films as an alternative to conventional synthetic packaging materials. Chitosan nanoparticles (CSNP) were produced via ionic gelation method using sodium tripolyphosphate (TPP) and deacetylated chitosan. Zein nanoparticles (ZNP) were synthesized based on antisolvent procedure in the presence of sodium caseinate (SC) to enable dispersion in water. Both plain and nanoparticle added WPI films were prepared by solution casting method. Water vapor barrier and mechanical properties of films were measured and the improvements in these properties with nanoparticle addition was further investigated through surface wetting, morphological, viscoelastic and thermal properties of the films. Both nanoparticles significantly decreased the water vapor permeability (WVP) and improved the mechanical properties of the WPI film. The highest enhancement in barrier and mechanical properties of the WPI films were recorded with 20% (w/w of WPI) CSNP and 120% (w/w of WPI) ZNP addition which corresponded to the maximum nanoparticle loading levels. At these loadings, the average WVP of pure WPI films loaded with ZNP and CSNP decreased by 84% and 57%, and the average tensile strength increased by 304% and 161%, respectively. On the other hand, the nanoparticles did not change the elongation at break significantly. ZNP was found more effective than CSNP in improving barrier and mechanical properties of the WPI films due to its hydrophobic nature and better dispersion in the protein matrix which allowed much higher loadings compared with the maximum loading levels achieved with CSNP. CSNP addition imparted antibacterial activity to the WPI films.Master Thesis Modeling of Hemodialysis Operation(Izmir Institute of Technology, 2008) Abacı, Hasan Erbil; Alsoy Altınkaya, SacideRecent studies have shown that the effectiveness of hemodialysis is based on module geometry, membrane properties and operating conditions. Various experimental work exist in the literature concentrated on the synthesis of new hemodialysis membranes. However, optimization of membrane structure requires extensive and time consuming experimentations. Therefore, mathematical models are neccessary that can be used to predict the performance of hemodialysis operation. In this study, a predictive theoretical model was developed to predict the solute concentrations in patient.s blood and optimize the efficiency of hemodialysis operation. The model takes into account simultaneous mass and momentum transfer along with the adsorption of rejected protein molecules on the surface of the membrane.Model predictions show that blood and dialysate flowrates are effective for all sizes of molecules. The change in structural properties of the membrane makes no effect on the total removal of urea beacause of its high clearance. On the other hand, a considerable increment in the clearance of larger molecular weight solutes occurs as the pore size and porosity of the membrane increases. The most important design parameter for dialysis unit which influence the solute clearances significantly is found to be the effective diameter among the fibers in the dialyzer.The model is extended to investigate the use of urease immobilized membranes on the efficiency of the hemodialysis operation. The results have shown that urease immobilization enhances the removal of urea from the blood and decreases the protein adsorption capacity of the polysulfone membrane.Model predictions are compared with different sets of clearance data available in the literature. The agreement is found to be satisfactory which suggests that the model can be used as a tool to design or test the performance of dialysis units.Master Thesis Modelling of Asymmetric Membrane Formation by Dry Casting Method(Izmir Institute of Technology, 2001) Özbaş, Bülent; Alsoy Altınkaya, SacideMany polymeric membranes are produced by phase inversion technique invented by Loeb and Sourirajan in 1962. One of the most challenging problems in membrane industry is to produce membranes with desirable structural characteristics which cause best performance for a specific application. The solution of this problem is facilitated by the development of mathematical models. The polymeric membrane formation process is a complicated process due to phase separation, simultaneous heat and mass transfer mechanisms controlled by complex thermodynamic and transport properties of polymer solutions. In this work, a fully predictive mathematical model developed by Alsoy (1998) was used to describe the mechanisms of membrane formation by dry casting method. Model equations consist of coupled unsteady state heat and mass transfer equations, film shrinkage as well as complex boundary conditions especially at polymer gas interface. A key component of the model is incorporation of multicomponent diffusion coefficients that consist of thermodynamic factors and self-diffusivities. The predictions from the model provide composition paths, temperature and thickness of the membrane. The beginning of phase transition was determined when compositions paths were plotted on the phase diagram. The model was applied to cellulose acetate/acetone/water system which is commonly used for asymmetric membrane formation. The model was used as a tool to optimize membrane formation process by investigating the effect of gas phase conditions, initial thickness and composition of the cast solution on the final membrane structure. The predictive ability of the model was evaluated by comparison with the data obtained from gravimetric measurements. Structural studies were conducted using scanning electron microscopy. Also, the permeability of prepared membranes to water vapor was measured using steady state technique. Both experimental and predicted results indicated that morphologies ranging from dense nonporous to asymmetric ones, in which a dense skin layer is supported by a porous layer, can be obtained with dry cast technique.Master Thesis Measurement and Modeling of Thermodynamic and Kinetic Data of Membrane Forming Systems(Izmir Institute of Technology, 2007) Arslan, Mine Özge; Alsoy Altınkaya, SacidePhase 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 Antimicrobial Polymeric Films for Food Packaging Applications(Izmir Institute of Technology, 2007) Gemili, Seyhun; Alsoy Altınkaya, SacideIn 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.