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Öğe Active packaging films based on poly(butylene succinate) films reinforced with alkaline halloysite nanotubes: Production, properties, and fruit packaging applications(Elsevier, 2024) Durmaz, Bedriye Ucpinar; Nigiz, Filiz Ugur; Aytac, AyseAlkaline 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.Öğe Application of Response Surface Methodology for Optimization of Copper Removal Using a Novel Polymeric Adsorbent(Springer, 2022) Unugul, Tuba; Nigiz, Filiz Ugur; Bozbas, Seda KarayunluDepending on the increase in the world population, the need for consumption and industrial resources is increasing day by day. In the wastewater caused by industrial production, a serious amount of heavy metals and water pollution caused by inorganic dyestuffs occur. In this study, graphene nanoplate/natural zeolite/sodium alginate bio-composite adsorbent was prepared and copper removal from wastewater by adsorption method was investigated. The characterization of the adsorbent was carried out by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and Brunauer-Emmett-Teller. In addition to batch adsorption tests, isotherm, kinetic and thermodynamic studies, experimental optimization was carried out with experimental parameters determined by the surface response methodology. Four experimental parameters (adsorbent dosage, metal concentration, solution pH, and contact time) were evaluated in a versatile way to determine the efficiency of heavy metal adsorption. The highest copper removal was obtained as 92.9% and 91.4%, respectively, in the experimental and model study at the adsorbent dosage of 0.5 g, the solution pH of 4.5, and the copper concentration of 20 ppm. The parametric results was meet with the optimization results with an R-2 value of 0.9834. The three most commonly used adsorption isotherms at 25 degrees C were calculated. The high R-2 value was found to be 0.9834 for the Langmuir isotherm model. It was determined that the adsorption kinetics matched the pseudo-second-order kinetics.Öğe Evaluation of Halloysite Nanotube-Loaded Chitosan-Based Nanocomposite Membranes for Water Desalination by Pervaporation(Springer Int Publ Ag, 2022) Unugul, Tuba; Nigiz, Filiz UgurIn this study, halloysite nanotube (HNT)-loaded chitosan-based nanocomposite membranes were synthesized and used for pervaporative desalination of water. Structural and morphological properties of the nanocomposite membranes were investigated. The effects of the HNT content, feed temperature, and feed NaC1 concentration on the flux and salt rejection were investigated. As the HNT content was increased, the degree of swelling decreased. At all temperature values, higher than 99% of salt rejections were achieved. The flux value increased from 1.63 to 4.89 kg/m(2)h, when the HNT content increased from 0 to 20 wt% at 30 degrees C. While the highest salt rejection value was obtained as 99.90% using the 10 wt% HNT-loaded nanocomposite membrane, the highest flux value was obtained as 5.81 kg/m(2)h using the 20 wt% HNT-loaded membrane at 50 degrees C. The pervaporation desalination results showed that HNT simultaneously increased the swelling resistance and the separation capability of the chitosan membrane.Öğe Grafen katkılı polilaktik asit membranıyla vakum membran distilasyon ile bor giderimi(2023) Nigiz, Filiz Ugur; Karakoca, BetülDesalinasyon 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.Öğe Graphene oxide-sodium alginate membrane for seawater desalination through pervaporation(Elsevier, 2020) Nigiz, Filiz UgurIn this study, graphene oxide (GO) filled sodium alginate membranes were synthesized and used for pervaporative desalination studies. The morphological, structural, thermal, and mechanical properties of membranes were determined. In the desalination studies, the effect of temperature and GO content on the separation performance was investigated. The addition of GO improved both the mechanical and thermal properties of the membrane as well as the separation performance. Higher than 99.4% of total rejection values were achieved by all the membranes at all studied temperatures. The flux value gradually increased from 1.63 kg/m(2).h to 4.89 kg/m(2).h when the GO concentration in the matrix increased from 0 wt% to 2 wt%. The highest flux of 8.11 kg/m(2).h with a rejection of 99.41% was obtained at 60 degrees C by using 2 wt% of GO loaded alginate membrane. The highest rejection of 99.95% with a flux of 3.46 kg/m(2).h was achieved at 40 degrees C by using 1 wt% of GO filled alginate membrane.Öğe Halloysite Nanotube doped poly lactic acid membrane preparation and seawater desalination(Elsevier, 2023) Nigiz, Filiz Ugur; Karakoca, BetulHalloysite nanotube (Hal) is a natural alumina silicate clay mineral. Hal is used in polymer composites for many reasons such as excellent physical and chemical properties, good miscibility, mechanical strength, antimicrobial properties, and cheapness. It is an important material used in water separation, especially due to its internal and external ionic structure hollow tubular structure. In this study, halloysite was used as a filler in polylactic acid polymer to produce a nanocomposite membrane for seawater purification. The morphological, physical, and chemical structures of the Hal filled, and unfilled membranes were investigated. The effect of HAL content (from 0% to 5% by weight), feed temperature (from 40 degrees C to 60 degrees C), NaCl concentration (from 2 wt% to 6 wt%), and the downstream pressure (from 10 mbar to 30 mbar) on the desalination performance were investigated as a function of flux and salt rejection. Hal improved the hydrophilicity, stability, mechanical strength, and the desalination performance of PLA membrane, significantly. The results showed that the highest desalination performance was achieved by 5 wt% of Hal-loaded membrane. The highest flux of 13.14 kg/m2.h was obtained accompanied by a rejection of 99.95%. The membrane was also used to purify seawater, and it was found that the permeate's ion concentrations met drinking water standards. The nanocomposite membrane was experimented over 100 h of testing, and no decrease in flux or salt rejection was seen.Öğe Improved Oil-Water Separation Performance of Polylactic Acid by Halloysite Nanotube Incorporation(2022) Nigiz, Filiz UgurIn this study, polylactic acid (PLA)-based nanocomposite membranes were prepared and used for the purification of simulated oil/water based wastewater. The lubricant oil (lubricating oil) was chosen as model oil. In order to increase the hydrophilicity of the membrane and improve its filtration performance, 0-20 wt.% of Halloysite nanotubes (HNT) were added into the PLA matrix. The effects of the HNT ratio on the oil/water swelling ratios (adsorption ratio), water flux, and oil rejection were determined. According to the results, optimal flux-oil rejection results were obtained with 5 wt.% of HNT incorporated nanocomposite membranes. The highest oil rejection of 94.9% was obtained using 5 wt.% of HNT incorporated membrane with a flux value of 1542.9 LMH.Öğe Increased hydrogen transport in microbial fuel cells by using copper based metal organic frameworks doped membrane(Pergamon-Elsevier Science Ltd, 2024) Nigiz, Filiz Ugur; Akel, MustafaThe 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.Öğe Optimization of bioethanol production from sugar beet processing by-product molasses using response surface methodology(Springer Heidelberg, 2024) Altinisik, Sinem; Nigiz, Filiz Ugur; Gurdal, Savas; Yilmaz, Kadir; Tuncel, Necati Baris; Koyuncu, SermetBioethanol 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 degrees 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.Öğe Pervaporative desalination using MIL 140 A loaded polylactic acid nanocomposite membrane(Elsevier, 2023) Nigiz, Filiz Ugur; Karakoca, BetuelIn 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 celcius), 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 celcius 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.Öğe Polyvinyl Alcohol/Zr-based Metal Organic Framework Mixed-matrix Membranes Synthesis and Application for Hydrogen Separation(Springer, 2024) Nigiz, Filiz Ugur; Unugul, TubaMembrane 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%.Öğe Preparation and Characterization an Active Carbon Adsorbent from Waste Mandarin Peel and Determination of Adsorption Behavior on Removal of Synthetic Dye Solutions(Springer International Publishing Ag, 2020) Unugul, Tuba; Nigiz, Filiz UgurIn this study, carbonized mandarin peel (CMP) was prepared and characterized and the adsorption behavior of the activated carbon for methylene blue (MB) and methyl orange (MO) removal was investigated. Adsorbent (CMP) was characterized by means of scanning electron microscopy (SEM-EDS), X-ray diffraction (XRD), thermo-gravimetric analyses (TGA), and Fourier transform infrared spectroscopy (FTIR). In the adsorption studies, the effects of initial dye concentration, solution pH, adsorbent dosage, and contact time on dye removal were investigated. In the same conditions, MB showed higher adsorption capacity than that of the MO. Therefore, the isotherms, kinetics, and thermo-dynamical adsorption studies were performed for MB. The appropriate adsorption isotherm for MB using CMP was determined as Langmuir isotherm. The kinetic values are well defined by the pseudo-second order kinetic model. The highest MB removal of 99.77% was obtained with CMP concentration of 5 g/L when the dye concentration was 5 mg/L at pH value of 6.9. After solvent regeneration, the adsorbent maintained 95.17% of its regeneration activity. The results show that CMP can be used as a low-cost and natural adsorbent to remove synthetic dye from the effluent of the textile wastewater.Öğe Solar light driven photochromic membranes with viologen additives in PVDF/PVP matrix(Frontiers Media Sa, 2024) Tohtayeva, Jahan; Altinisik, Sinem; Akgun, Mert; Nigiz, Filiz Ugur; Koyuncu, SermetThis study explores the synthesis and characterization of photochromic Polyvinylidenefluoride/Polyvinylpyrrolidone (PVDF/PVP)-based membranes, prepared through an in situ thiol-ene click reaction by incorporating viologen derivatives with different counter ions. Viologens are well-known for their light-sensitive properties and ability to change color, making them useful in various optoelectronic applications. The membranes developed in this study exhibit significant improvements in their interactions with light as a result of improved morphology and enhanced ionic conductivity (approximate to 4 x 10-4 S cm-1) with higher porosity (Ra: 11.26-33.76 nm) compared to conventionally prepared membranes. These membranes show the ability to block almost all ultraviolet (UV) and a 90% of visible light after irradiation. Thanks to these properties, the membranes undergo visible color changes when exposed to sunlight, making them suitable for photochromic and thermochromic applications. The findings of this study could contribute to the development of innovative coating materials that enhance energy efficiency, potentially being applied to buildings, automotive windows, and other surfaces.
