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A comparative study on removal of boron via pervaporation and vacuum membrane distillation using zirconium metal-organic framework-loaded poly(lactic acid) membrane
(Springer Heidelberg, 2025) Nigiz, Filiz Uğur; Tan, Burcu; Bektaş, Tijen Ennil; Karakoca, Betül
Boron mineral is very important for the life. However, exceeding the standards of boron minerals, especially in water to be used as domestic water, causes health and environmental problems. The commercial method used to separate boron minerals from water is reverse osmosis. In recent years, promising results have been obtained with the membrane distillation (MD) method. However, another method that is as effective as this method is pervaporation (PV). The most important component that affects performance in both methods is the membranes. In this study, zirconium-based metal organic framework (MOF) material was synthesized and added to the polylactic acid (PLA) membrane and boron was removed by pervaporation and membrane distillation methods. While the selective layered asymmetric membrane was prepared for pervaporation, porous membranes were prepared for membrane distillation. The effect of MOF additive on the morphology, mechanical strength, and separation properties of the membrane was investigated. Additionally, the effects of boron concentration and temperature on the separation performance in both methods were examined. As a result, the mechanical strength of membranes with MOF added increased significantly from 2.41 to 8.20 MPa. 99.9% boron removal was achieved in both methods. While the highest flux value was calculated as 8 kg/m2h in pervaporation at 6 ppm boron concentration, it was calculated as 11.33 kg/m2h in membrane distillation.
Active packaging films based on poly(butylene succinate) films reinforced with alkaline halloysite nanotubes: Production, properties, and fruit packaging applications
(Elsevier, 2024) Uçpınar Durmaz, Bedriye; Nigiz, Filiz Uğur; Aytaç, Ayşe
Alkaline treated halloysite nanotubes (aHal) were introduced into poly(butylene succinate) (PBS) matrix using melt blending and solvent casting techniques to enhance the functional properties. The films were characterized for morphological, thermal, mechanical, antibacterial, barrier, and ethylene scavenging properties for their fresh food packaging use. The films exhibited ethylene scavenging performance because of the increased lumen diameter of aHal. The highest ethylene scavenging performance was achieved at 5 wt% aHal (5-aHal) loading for both production methods. The amount of ethylene in the gas-tight container decreased by 80% and 75% in the presence of extruded and solvent-cast 5-aHal, respectively. While PBS/aHal films have mechanical properties comparable to other films recommended for food packaging, extruded films were more flexible and durable than solvent-cast films. In addition, extruded films were found to have a higher water vapor barrier. A packaging test has also been carried out on sliced tomatoes and apples stored at room conditions for 7 days. 5-aHal films showed the best performance in extending the fruit's shelf life. Considering all the results, the melt blending films offer superior performance. Bio-based PBS/aHal films have the capability to contribute significantly to the food safety by serving as eco-friendly, active food packaging materials.
Biyokompozit membran ile yağlı atık suların saflaştırılması
(2022) Nigiz, Filiz Uğur
Bu çalışmada, biyobozunur polilaktik asit polimerinin yağ-su ayırımındaki performansı incelenmiştir. Çalışma kapsamında membranlar hazırlanmış ve vakum filtrasyon işlemi uygulanmıştır. Membranın yağ ve suya olan ilgisi, yağ ve su içindeki şişme testleriyle belirlenmiştir. Membranın hidrofilitesini arttırmak ve performansını iyileştirmek için içine halosit nanotüp (HNT) eklenmiş ve nanokompozit haline getirilmiştir. Membranın yüzey morfolojisi taramalı elektron mikroskobuyla (SEM) ile belirlenmiştir. Çalışmada halosit nanotüp oranının (%0-20), yağ/su şişme oranlarına (adsorpsiyon oranına), membrandan geçen sıvı akısına ve yağ reddine etkisi belirlenmiştir. Çalışmada model yağ olarak soya yağı seçilmiştir. Soya yağı-su emülsiyonu hazırlanarak ayırım testleri yapılmıştır. Elde edilen sonuçlara göre soya yağı ayırımında %5 HNT katkısında %97.2 saflıkta su alt akımdan elde edilmiştir. Yüksek ayırımın yanında 1714.3 üzerinde saatte litre bazında su akısı elde edilmiştir.
COMPOSITE HYDROXYL ETHYL CELLULOSE MEMBRANE FOR HYDROGEN PURIFICATION
(Bartın Üniversitesi, 2020) Ünügül, Tuba; Nigiz, Filiz Uğur
Hydrogen is an important fuel production chemical that is used both for generating electrical energy in fuel cells and in which many chemicals can be produced. Hydrogen can be produced either by chemical methods from petrochemical products or from biomass by fermentation. However, in order to use hydrogen as a fuel source, it must be separated from other waste gases. Although there are many methods used for separation, the most efficient, clean and inexpensive method is membrane gas separation. The effectiveness of this process depends on the membrane produced. In this study, hydroxy ethyl cellulose (HEC) and polystyrene sulfonic acid (PSSA) membranes was synthesized for selective separation of hydrogen from carbon dioxide. In order to increase the hydrogen selectivity, natural zeolite was incorporated into polymer matrix. The effects of HEC/PSSA ratio, and zeolite content on gas permeability and hydrogen selectivity were investigated. As the PSSA ratio increased in HEC matrix, both the hydrogen permeability and selectivity increased. The content of zeolite also increased the hydrogen gas separation performance. The highest selectivity of 5.69 was achieved when the HEC/PSSA ratio was 1 and the zeolite content was 20% (w/w). The separation results showed that the PSSA and natural zeolite showed a positive effect on hydrogen purification and the membranes can be considered as a hydrogen purification material.
Fabrication and characterization electrospun clinoptilolite filled polylactic acid composite membrane: purification of multiple impurities from water
(Elsevier, 2025) Kahraman, Seniyecan; Katırcı, Ayşenur; Aytaç, Ayşe; Veli, Sevil; Nigiz, Filiz Uğur
In this study, electrospun clinoptilolite (Clp)- polylactic acid (PLA) nanocomposite membranes were produced and used for dyestuff (methylene blue, MB), oil (soybean oil), microplastic (Polyamide 66, PA66), and Linear Alkyl Benzene Sulfonate (LAS) rejection from simulated gray water. The membrane's physical, chemical, thermal, morphological, mechanical, and antimicrobial properties were investigated regarding Clp incorporation. According to the characterization results, the empirical porosity of the membrane was found to be between 79 % and 83 %. The PLA membrane's water uptake capacity, surface hydrophilicity, and mechanical strength were improved with Clp incorporation. All membranes show antimicrobial effects against both gram-positive and negative bacteria. According to the filtration test results, MB separation was above 90 %. The highest oil rejection was found to be 87.84 % using 4 wt% Clp loaded membrane. All membranes rejected 100 % of microplastic. 66.6 % of LAS rejection was achieved with 3 wt% Clp loaded membrane. All separation and characterization results show that Clp-doped PLA membranes have the potential to be used as a filtration membrane that can simultaneously separate all impurities from water.
Fabrication and Characterization of MOF-Doped Composite Polyvinyl Alcohol Membrane and Investigation of Its Potential for Carbon Dioxide Separation from Flue Gas
(Tokat Gaziosmanpaşa Üniversitesi, 2025) Nigiz, Filiz Uğur
The objective of this work was to prepare glassy polymeric membranes for the purpose of separating carbon dioxide from flue gas mixtures and to conduct gas separation experiments using these membranes. Metal organic framework (MOF) was added to the membranes to improve their ability to select carbon dioxide, thereby enhancing the strength of the membrane and gas separation performance. Therefore, MIL 140B was synthesized, composite polyvinyl alcohol membranes were prepared, characterized and tested for carbon dioxide nitrogen removal. Increasing MIL 140B content significantly increased the tensile strength and mechanical strength. However, a significant decrease in mechanical strength was observed at 4 wt.% of filler doped membrane. In gas separation studies, first single gas and then mixed gas tests were performed. In both cases, MIL 140B additive increased both carbon dioxide selectivity and permeability. MIL 140B ratio increased from 0 wt.% to 4 wt.%, CO$_2$ permeability increased from 92 Barrer to 179 Barrer and selectivity increased from 41.4 to 58.7.
Grafen katkılı polilaktik asit membranıyla vakum membran distilasyon ile bor giderimi
(Gümüşhane Üniversitesi, 2023) Nigiz, Filiz Uğur; Karakoca, Betül
Desalinasyon ve bor giderimi için membran teknolojilerine son yıllarda ilgi duyulmaktadır. Günümüzde membran bazlı ayırma prosesleri, çevre dostu olmaları ve enerji/maliyet tüketimindeki verimlilikleri nedeniyle tercih edilmektedirler. Bu yeni teknolojilerden biri de membran distilasyondur. Henüz akademik seviyede olan araştırmalar sonucunda membran distilasyon gibi ileri teknoloji ile %99,99 üzeri saflaştırma ve giderim yapmak mümkündür. Bu çalışmada, biyobozunur polimerlerden olan saf ve grafen katkılı polilaktik asit (PLA) membranlar üretilerek membran distilasyon tekniği ile sulardan bor giderimi yapılmıştır. Sıcaklığın, bor konsantrasyonunun, grafen oranının bor reddi ve su akısı değerlerine etkisi belirlenmiştir. Sonuç olarak tüm sıcaklıklarda ve tüm grafen katkılı PLA membranlarla %99 üzeri bor retleri elde edilmiştir. Özellikle grafen katkısıyla akı değerleri 13 kg/m2.h olarak elde edilmiştir.
Hydrogen purification using natural zeolite-loaded hydroxyethyl cellulose membrane
(John Wiley and Sons Ltd, 2022) Ünügül, Tuba; Nigiz, Filiz Uğur
In this study, natural zeolite-loaded hydroxyethyl cellulose (HEC) mixed-matrix membranes were produced and used for separation of hydrogen (H2) from carbon dioxide (CO2). Structural, thermal, and morphological properties of the mixed-matrix membranes were investigated. The effects of zeolite addition and trans-membrane pressure on the gas permeability and H2/CO2 selectivity have been evaluated. As the zeolite ratio in the membrane increased, H2/CO2 selectivity increased. The highest H2/CO2 selectivity of 8.85 was obtained using 20 wt% of natural zeolite-loaded membrane at a constant pressure difference of 4 bar. The selectivity and permeability values of 20 wt% zeolite-loaded membrane exceeded the Robeson's upper bound curve-1991.
Improved packaging performance of olive tree-based biochar-loaded poly(lactic acid) films
(Bulgarska Akademiya na Naukite, 2024) Nigiz, Filiz Uğur; Özyörü, Z.İ.; Balcı, S.
Petroleum-containing packaging materials have created serious ecological problems for the environment due to their resistance to biological degradation. In this context, the use of biodegradable films as alternative to packaging materials is gaining importance. Among various biopolymers, poly(lactide) (PLA) is an effective and durable material. However, the mechanical strength of PLA polymer is low. In addition, its vapor permeability is high, which limits the use of this material. Biochar (BC) is an additive that can be produced from many wastes and acts as a fertilizer in the soil. Adding it to the PLA material makes the packaging film completely compostable and improves its properties. In this study, biochar was synthesized from olive pruning waste by the slow pyrolysis method. Biochar was added to the PLA films in different ratios (5, 10, 15, 20 wt.%). The packaging properties of the films were investigated. Specific surface area (BET), biochar yield, and ash content, as well as tensile strength, swelling, water vapor permeability, and opacity of the films were determined. Owing to the high lignin rate and low volatile matter in the olive branch, biochar was produced with a yield of 29.75%. When the BC concentrations of the films increased, the water vapor permeability capacity gradually decreased from 4.43% to 1.36%. The maximum tensile strength value was obtained as 14.91 MPa for 5 wt.% biochar-loaded PLA films. © 2024 Bulgarian Academy of Sciences, Union of Chemists in Bulgaria.
Increased hydrogen transport in microbial fuel cells by using copper based metal organic frameworks doped membrane
(Pergamon-Elsevier Science Ltd, 2024) Nigiz, Filiz Uğur; Akel, Mustafa
The potential of microbial fuel cell (MFC) technology to generate electricity simultaneously with treating organic and inorganic has gained importance, recently. The efficiency of the MFC system varies according to the types of MFCs, types, and areas of electrodes, separators, substrate, etc ... In this study, a dual-chamber (H-type, membrane separator) MFC system was set up and used for electricity production from animal manure. A copper-based metal organic framework (Cu-MOF) was synthesized and used in a polyvinylidene fluoride (PVDF) membrane matrix. The water uptake (WU) value, mechanical strength, and cation exchange capacity (CEC) of the membranes were investigated. MFC performances of the pristine and Cu-MOF incorporated nanocomposite membranes were also performed. Effects of the Cu-MOF ratio (from 1 to 4 wt percentage), the operating time, and external resistance on voltage output and power density were evaluated. As a result, the incorporation of CuMOF enhanced the CEC from 1.04 mmol/g to 1.77 mmol/g, and the mechanical strength from 0.55 MPa to 1.15 MPa. The highest power density value was obtained as 4.62 mW/m 2 by using 3 wt% of Cu-MOF loaded membrane.
OLEİK ASİTTEN BİYODİZEL ÜRETİMİNİN KESİKLİ REAKTÖR VE MEMBRAN REAKTÖRDE KARŞILAŞTIRILMASI
(Bartin University, 2024) Erden, Hanife; Nigiz, Filiz Uğur; Kahraman, Seniyecan
Son yıllarda biyodizel, fosil yakıtlara sürdürülebilir bir alternatif olarak daha fazla ilgi görmektedir. Biyodizel, petrol dizel yakıtına kıyasla daha düşük egzoz emisyonlarına ve toksisiteye sahiptir. Bu çalışmada oleik asit ve etanol arasında esterleşme reaksiyonu ile biyodizel üretimi kesikli reaktör ve membran reaktörde gerçekleştirilmiştir. Kesikli reaktörde ve membrane reaktördeki dönüşümler karşılaştırılmıştır. Membran reaktörlerin geleneksel reaktörlere göre avantajı gösterilmiştir. Katalizör olarak homojen katalizör olan sülfürik asit kullanılmıştır. Membran reaktörde kullanılmak üzere hidrofilik olan PVA membranı sentezlenmiştir. Katalizör konsantrasyonunun (ağırlıkça %2, %4, %6), etanol/oleik asit molar oranının (3, 6, 9) ve sıcaklığın (45°C, 55°C, 65°C arası) oleik asit dönüşümüne etkisi kesikli reaktörde incelenmiştir. Optimizasyon ile belirlenen noktada aynı reaksiyon membran reaktörde de gerçekleştirilmiştir. Reaksiyonlar dört saat sürdürülmüştür. Hem parametrik hem de optimizasyon sonuçlarına göre kütlece katalizör konsantrasyonunun dönüşüme etkisinin düşük olduğu, sıcaklık ve molar besleme oranının ise asit dönüşümüne etkisinin yüksek olduğu görülmüştür. Kesikli reaktörde En yüksek dönüşüm değeri % 85,5 ile 65 °C sıcaklıkta, alkol: asit molar besleme oranı 6:1 iken, %4 katalizör konsantrasyonu ile elde edilmiştir. Etanol/oleik asit molar oranı 3, sıcaklık 55 °C ve katalizör oranı ağırlıkça %4 olduğunda kesikli reaktörde %50 oranında dönüşüm elde edilirken, membran reaktörde %75 oranında elde edilmiştir. Bu sonuçlara dayanarak aynı çalışma koşullarında, membran reaktörde elde edilen asit dönüşüm sonuçları kesikli reaktörlerden %26 oranında arttığı görülmüştür
Optimization and modeling of biodiesel production from oleic acid in plug flow reactor
(Amasya University, 2024) Erden, Hanife; Nigiz, Filiz Uğur
In recent years, biodiesel has been preferable to fossil fuels because of its renewability, biodegradability, and producibility from various wastes. In this study, the esterification reaction between oleic acid and methanol was carried out in the presence of sulfuric acid, which is a homogeneous acid catalyst, to produce biodiesel. Experiments were carried out in a plug flow reactor (PFR) and a batch reactor. The experimental conditions with the highest conversion obtained in the PFR were determined and applied to the batch reactor and results were compared. The effects of temperature (45, 55, 65 in Celsius), catalyst concentration (2%, 4%, 6% by weight), and methanol/oleic acid mole ratio (3, 6, 9) on oleic acid conversion were examined in the PFR. Retention times at different flow rates were calculated to determine the reaction time in the PFR and reactions were carried out between 2 and 6 minutes. In the reactions carried out in the PFR, the highest conversion value was obtained as 97.33% under conditions where the catalyst concentration was 6% by weight, the temperature value was 55oC and the alcohol/acid mole ratio was 6:1. These conditions were applied to the batch reactor and the conversion value was found to be 50%. When the experimental results were examined, it was seen that the effect of temperature and alcohol/acid ratio on the conversion was greater than the effect of the catalyst concentration on the conversion. The modeling of oleic acid/methanol esterification, i.e., biodiesel production, at specific boundary values was found to follow a cubic dependence in the general dependence equation via Response Surface Methodology.
Optimization of bioethanol production from sugar beet processing by-product molasses using response surface methodology
(Springer Science and Business Media Deutschland GmbH, 2025) Altınışık, Sinem; Nigiz, Filiz Uğur; Gürdal, Savaş; Yılmaz, Kadir; Tuncel, Necati Barış; Koyuncu, Sermet
Bioethanol production from renewable biomass sources has garnered significant interest due to its potential as a sustainable alternative to fossil fuels. In this study, we investigated the optimization of bioethanol production from molasses, a by-product of the sugar production process using Saccharomyces cerevisiae through Response Surface Methodology (RSM). Initially, the fermentation process was optimized using RSM, considering four independent variables: substrate concentration, pH, temperature, and fermentation time. Subsequently, the effects of these variables on bioethanol yield were evaluated, and a quadratic model was developed to predict the optimum conditions. Analysis of variance (ANOVA) indicated a high coefficient of determination (R2) for the model, suggesting its adequacy for prediction. The optimized conditions for bioethanol production were determined as follows: substrate concentration of 200 g L−1, pH of 5.0, temperature of 30 °C and fermentation time of 72 h. Under these conditions, the predicted bioethanol yield was 84%. Overall, this study demonstrates the successful application of RSM for optimizing bioethanol production from molasses using S. cerevisiae, highlighting its potential as a promising feedstock for biofuel production.
Optimization of Pervaporative Desalination with Zirconia Based Metal Organic Framework Filled Nanocomposite Membrane
(Springer, 2023) Ünügül, Tuba; Nigiz, Filiz Uğur; Karakoca, Betül
In this study, a freestanding asymmetric polylactic acid-based MIL 140A loaded nano-composite membranes were prepared and tested for pervapoative desalination. The chemical and morphological properties of the membranes were characterized by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The effects of permeate pressure (10, 20, 30 mbar), feed temperature (40, 50, 60 °C), and NaCl concentration (2, 4, 6 wt.%) on the flux and the rejection were experimentally determined. In order to determine the effect of operation parameters on desalination, an optimization study was done using the Box–Behnken design (BBD) of Response Surface Method (RSM) and a statistical model was created. In addition to optimization, experimental studies were also carried out between the limit factors and the results were compared with the model. The highest flux was obtained as 5.40 kg/m2h accompanied with the rejection of 99.87% when at the lowest NaCl content of 2 wt.%, and the highest temperature of 60 °C. The rejection value was greater than 99.7% in all experiments. The highest flux was obtained as 5.40 and 5.44 kg/m2h, respectively, in the experimental and model study at the NaCl content of 2 wt.%, the temperature of 60 °C, and downstream pressure of 10 mbar. It was seen that the most suitable statistical model equation for the experimental results was the second-order quadratic model, and the experimental data were agreed with 99.41% of accuracy.
Optimization of Sodium Alginate?Graphene Nanoplate?Kaolin Bio?composite Adsorbents in Heavy Metal Adsorption by Response Surface Methodology (RSM)
(Springer, 2022) Ünügül, Tuba; Nigiz, Filiz Uğur
In this study, graphene nanoplate-kaolin-sodium alginate (GKS) bio-composite adsorbent was prepared, and the copper removal from wastewater by the adsorption method was investigated. Characterization of adsorbent was carried out using a scanning electron microscope, Fourier transforms infrared spectroscopy, and thermo-gravimetric analysis methods. In addition to the parametric adsorption studies, experimental optimization was also applied with parameters determined by the central composite design of response surface methodology (RSM). Effects of copper concentration (from 10 to 50 ppm), pH (from 3 to 7), and adsorption dosage (from 0.05 to 0.15 g/L) were investigated to determine the optimum design points. In order to determine the efficiency of heavy metal adsorption, four experimental parameters (adsorbent dosage, metal concentration, pH, and contact time) were evaluated. As a result, the highest removal of 92.12% was obtained when the heavy metal concentration was 10 mg/L, the adsorbent dosage was 0.15 g, the solution pH was 7, and the contact time was 180 min. Adsorption isotherm studies were also carried out. The appropriate adsorption isotherm for copper removal using GKS was determined as Langmuir isotherm. According to the optimization results, the quadratic model with an R2 of 0.9946 was found to be the most suitable model.
Pervaporatif Desalinasyon Için Polilaktik Asit Temelli Karma Matrisli Membranların Üretimi Ve Deniz Suyu Saflaştırılmasında Kullanımı
(2022) Nigiz, Filiz Uğur; Bektaş, Tijen Ennil; Karakoca, Betül; Tan, Burcu
Su, canlı yaşamı için çok önemlidir. Fakat küresel ısınma ve insan faktörlü kirlilikler nedeniyle su kaynakları kirlenmekte veya yok olmaktadır. Bu yüzden de dünyanın büyük bir kısmını kaplayan deniz sularını saflaştırarak içilebilir ve kullanılabilir su elde etmek amaçlamıştır. Bu projede ise deniz suyunu saflaştırma için çok yeni bir yöntem olan pervaporatif desalinasyon işlemi kullanılmıştır. Bu teknolojide kullanılan membranlarda temel malzeme olarak doğal kaynaklardan elde edilebilen Polilaktik asit (PLA) polimeri kullanılmıştır. Aynı zamanda MOF malzemelerinden olan MIL-140A ve MIL-140B sentezi yapılarak membranların yapısına dahil edilmiştir. Killerden olan HNT malzemesi de PLA membranların yapısında dahil edilmiştir. Bu membranların karakterizasyon testleri yapılmıştır. Pervaporasyon ile desalinasyon çalışması yapılmıştır. En yüksek akı ve tuz reddi %3 MIL 140A katkılı ve %5 HNT katkılı membranlarda elde edilmiştir. Aynı membranlar ile optimizasyon çalışması yapılmıştır ve %99 üzeri doğrulukta istatistiksel bir model oluşturulmuştur. Ardından %3 MIL-140 katkılı ve %5 HNT katkılı PLA membanlar çok ince (30 µm) olarak hazırlanmıştır. 60°C sıcaklıkta, 10 mbar basınçta ve %2 NaCl konsantrasyonda pervaporatif desalinasyon sonucunda %5 HNT katkılı membranda 13.14 kg/m2h akı ve %99,95 tuz reddi elde edilmiştir, %3 MIL-140 katkılı membranda ise 12.2 kg/m2h akı ve %99,92 tuz reddi elde edilmiştir. Bu membranlar ile deniz suyu saflaştırma işlemi yapılmış ve birçok kirleticinin içme suyu standartında ayrıldığı gözlenmiştir. Membranlar 100 saatin üzerinde kararlılık testine alınmış ne akı ne de tuz reddinde önemli düşüşler görülmemiştir.
Pervaporative desalination using MIL 140 A loaded polylactic acid nanocomposite membrane
(Elsevier, 2023) Nigiz, Filiz Uğur; Karakoca, Betül
In this study, freestanding asymmetric MIL 140 A loaded polylactic acid (PLA)-based membranes were prepared and tested for pervapoative desalination. Membranes were characterized using different chemical and physical techniques. Desalination test was carried out with NaCl-water solution. The effects of MIL 140 A concentration (0, 1, 2, 3, 4 wt%), feed temperature (40, 50, 55, 60 ℃), NaCl concentration (2, 3, 4, 5, 6 wt%), and the downstream pressure (10, 15, 20, 25, 30 mbar) on the flux and the rejection were determined. As a result, MIL 140 A incorporation improved the hydrophilicity, durability, and the mechanical strength of PLA membrane. According to the results, a flux of 12.2 kg/m2.h with the rejection of 99.92 % was achieved by 3 wt % of MIL 140 A filled membrane at 60 ℃ with 10 mbar downstream pressure. A real sea water separation was also made with the 3 wt% of MIL 140 A loaded membrane and it was observed that the ion concentrations of the permeate were in drinking water standards. The prepared membrane was tested more than 160 h and no flux and salt rejection decrease was observed except for experimental errors.
POLİLAKTİK ASİT TEMELLİ MEMBRANIN MORFOLOJİSİNİN DESALİNASYON PERFORMANSINA ETKİSİ
(Bartın Üniversitesi, 2021) Karakoca, Betül; Nigiz, Filiz Uğur
Nüfus artışı, küresel ısınma ve insanların sebep olduğu kirlilikler nedeni ile su kaynaklarımız azalmaktadır. Dünya üzerindeki sular doğrudan kullanılamayan tuzlu sulardan oluşmaktadır. Bu nedenle mevcut su kaynaklarının kullanımı için ayırma işlemlerinin kullanılması son yıllarda önem kazanmaktadır. Pervaporasyon tekniği, tuzlu sulardan saf su elde etmek için yeni gelişen bir tekniktir. Bu çalışmada, deniz suyunun saflaştırılması için Polilaktik asit (PLA) polimeri ile membranlar üretilmiş, membranın hidrofilitesini ve ayırma performansını iyileştirmek, aynı zamanda kararlılıklarını da korumak polietilen glikol (PEG) polimeri eklenmiştir. Çalışma kapsamında, gözeneksiz yoğun ve asimetrik olmak üzere iki farklı membran hazırlanmıştır ve morfolojik yapı farklılıklarının desalinasyon performansına etkileri incelenmiştir. Taramalı elektron mikroskobu (SEM) ve temas açısı testi ile membranlar karakterize edilmiş, ardından tuzlu su desalinasyon testleri yapılmıştır. Sonuç olarak membranın hidrofobitesi azaltılmış bu sayede akı değerleri artmıştır. Tüm membranlar %99 üzerinde tuz reddi elde edilmiştir. En iyi sonuçlar ise %5 PEG içeren PLA membran ile elde edilmiştir. Bu membranın akısı 1,57 kg/m2h, tuz reddi ise %99,98 olarak hesaplanmıştır. Üretilen membranın asimetrik yapıda olması akıyı arttırmış buna rağmen yüksek saflıkta su elde edilmesini sağlamıştır
Polyvinyl Alcohol/Zr-based Metal Organic Framework Mixed-matrix Membranes Synthesis and Application for Hydrogen Separation
(Springer, 2024) Nigiz, Filiz Uğur; Ünügül, Tuba
Membrane gas separation is an environmentally friendly and economical method used to separate valuable gases, industrial process gas wastes, and carbon dioxide from mixed gases. The most important part of this method is the membranes. Gas separation membranes are expected to have high separation and permeability performance, high mechanical strength, easy and fast production capability, and low prices. Polymer-based membranes are mostly preferred depending on the ease of modification capability. In this study, a zirconium-based metal organic framework (Zr-MOF, MIL-140 A) was synthesized and used as a filler within polyvinyl alcohol (PVA) matrix for the selective separation of hydrogen (H2) from carbon dioxide (CO2). The effect of MIL-140 A addition on the mechanical, structural, and morphological properties of PVA was evaluated. The MIL-140 A significantly improved the mechanical strength of the membrane. According to the gas separation results, the increasing concentration of MIL-140 A increased the selective separation performance of the nanocomposite membrane. The highest mechanical strength (43.1 MPa) and best film-forming ability were obtained with 3 wt% MIL-140 A loaded membrane. The ideal H2/CO2 selectivity and hydrogen permeability were obtained as 5.6 and 944 Barrer, respectively at 2 bar feed pressure and room temperature. The highest ideal H2/CO2 selectivity was obtained as 6.3 with the H2 permeability of 959 Barrer when the MIL-140 A ratio was 4 wt%.
Production of potassium hydroxide-activated biochar and its use as a filler in polylactic acid for food packaging
(Amasya University, 2024) Nigiz, Filiz Uğur; Özyörü, Zeynep İrem; Balcı, Serhat
Petroleum-containing packaging materials of the past and present have created serious ecological problems for the environment due to their resistance to biodegradation. In this context, researches have been conducted to promote the use of biodegradable films as an alternative to packaging materials. Among various biopolymers, poly(lactide) (PLA) has found application in the food industry owing to its promising properties and is currently one of the most industrially produced bioplastics. In this study, biomasses of olive pruning wastes, which are abundant in the Çanakkale region, were converted into biochar (BC) by slow pyrolysis, and their characterization was examined by adding them to PLA at different rates (5%, 10%, 15%, 20% by mass). Specific surface area analysis (BET), scanning electron microscopy (SEM) analysis, biochar yield, ash content, surface contact angles, and antimicrobial activity of film depending on the BC concentration were evaluated. As a result, potassium hydroxide (KOH) activated BC was successfully synthesized with a surface area of 1022 m2/g. The hydrophobicity of films was improved with increasing BC ratio. Also, the film shows good antimicrobial activity toward gram-negative bacteria.

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