WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 4Citation - Scopus: 5Antifouling Polydopamine-Modified Poly (ether Sulfone) Membrane Immobilized With Alumina-Calcium Oxide Catalyst for Continuous Biodiesel Production(Elsevier, 2023) Güngörmüş, Elif; Şeker, Erol; Alsoy Altınkaya, SacideBiodiesel is an alternative biofuel that can be blended with conventional petroleum-derived diesel fuel to partly reduce the dependence on the imported oil. Catalytic membrane reactors are promising candidates for sustainable biodiesel production. Herein, we report a novel catalytically active polydopamine-modified poly (ether sulfone) (PES) membrane immobilized with an alumina-calcium oxide catalyst. The reaction temperature, butanol to canola oil ratio, and transmembrane pressure applied through the membrane were optimized with response surface methodology and Box-Behnken design. In contrast to all previous catalytic membrane studies for biodiesel production, we used butanol as a co-reactant to improve the winter problems of biodiesel made with methanol. FTIR and SEM-EDX analysis confirmed the successful immobilization of the catalyst. At the end of 30 days of storage in the reactant mixture, 95% of the catalyst loaded to the membrane was still on the surface, and biodiesel yield values and butanol flux of the membrane did not change. We compared the batch and flowthrough operation modes by measuring the catalytic activity of membranes under static and dynamic conditions within 24 h (8-cycle). The biodiesel yield under dynamic condition decreased in the first three cycles from 54.54 +/- 0.65% to 47.31 +/- 0.70% and then stayed constant, whereas a continuous decrease from 25.42 +/- 0.57% to 17.19 +/- 0.58% was observed under static condition. In each cycle, the equilibrium limitation for the yield was overcome only when the membrane was operated under pressure. The main reason for the decrease in catalytic activities was the fouling on the catalyst surface which was quickly removed by backwashing with butanol. It is concluded that catalytic membranes with antifouling properties and alcohol stability can make biodiesel production more cost-effective and environmentally friendly.Article Citation - WoS: 1Citation - Scopus: 2A New-Generation Poly (ether Imide Sulfone) Based Solvent Resistant Ultrafiltration Membrane for a Sustainable Production of Silica Nanopowder(Elsevier, 2023) Güngörmüş, Elif; Alsoy Altınkaya, SacideThe work presented here demonstrated the feasibility of using a membrane to improve the sustainability of silica nanopowder production. Due to superior chemical resistance, high thermal-oxidative stability, and good processability, poly (ether imide sulfone) has been used for membrane production and modified with amine-functionalized TiO2 nanoparticles. The membrane demonstrated good long-term leaching stability in 40% ethanol and silica synthesis solution and maintained its permeability and rejection characteristics under static and dynamic conditions. Additionally, the high antifouling property of the membrane allowed recovering 99.5% of the nanoparticles. Backwashing with water resulted in a high flux recovery ratio (>93%), and gravity-settling without energy can easily separate silica nanoparticles and water in the backwashing solution. Compared to classical freeze-drying and oven-drying methods, integrating membrane into silica nanopowder production can reduce energy consumption by a factor of 81 and 53. At the same time, the utility cost can be saved by 80% and 69%. Additionally, the solvent and catalyst recovered in the permeate stream can be reused in the synthesis, reducing disposal and purchasing costs. In conclusion, membrane-assisted nanopowder production can minimize the adverse effects caused by commonly used conventional drying methods and make the process more sustainable and environmentally friendly.Article Citation - WoS: 54Citation - Scopus: 62A Positively Charged Loose Nanofiltration Membrane Fabricated Through Complexing of Alginate and Polyethyleneimine With Metal Ions on the Polyamideimide Support for Dye Desalination(Elsevier, 2021) Metecan, Ayşe; Cihanoğlu, Aydın; Alsoy Altınkaya, SacideNowadays, loose nanofiltration (NF) membranes are preferred for dye desalination to achieve high dye/salt selectivity and enable filtration at low operating pressure. However, current fabrication techniques require rigorous reaction conditions and long preparation times. Herein, we used the chelating ability of the polyethyleneimine (PEI) and alginate with the metal ions to fabricate loose NF membranes via a facile approach. The positively charged polyamide imide (PAI)/PEI support was used to build the assembly. Direct attachment of Zn or Fe ions to the PEI chains did not result in a stable complex in the presence of a high salt concentration (1000 ppm NaCl). On the other hand, alginate coated on the support allowed building permanent assemblies after crosslinked with Fe3+ and Zn2+ transition metal ions. The PAI/PEI-Alg-Fe3+ membrane exhibited the highest permeability, excellent antifouling behaviour upon exposure to synthetic textile wastewater, and maintained long-term stability under static and dynamic conditions. Also, the same membrane rejected dyes and coloured substances in real wastewater sample during 72 h continuous filtration. With alginate metal complex formation on a suitable support, a scalable loose NF membrane was manufactured, demonstrating improved throughput value compared to current NF membranes.Article Citation - WoS: 14Citation - Scopus: 16Facile Fabrication of Anti-Biofouling Polyaniline Ultrafiltration Membrane by Green Citric Acid Doping Process(Elsevier, 2021) Güngörmüş, Elif; Alsoy Altınkaya, SacideThis study aimed to enhance the anti-biofouling property of the polyaniline (PANI) based ultrafiltration (UF) membrane by utilizing its self-acid doping ability. A naturally derived biodegradable agent, citric acid, was doped to the membrane by filtering at 1 bar. Acid doping increased the hydrophilicity, made the surface nearly electroneutral, and imparted biocidal characteristics to the membrane. Biofouling was simulated by filtering a suspension of E.coli and S.aureus through the membranes. Most fouling on the doped membrane was reversible and easily removed by simple washing, leading to a high flux recovery ratio. The SEM images taken after filtration and washing steps showed that the modified membrane surface was free of bacteria while many bacteria accumulated on the pristine membrane surface. The doped membrane was stored in 1 M NaCl solution for up to five months. A tiny amount of citric acid was lost from the membrane, and at the end of storage, the flux, rejection, and antibacterial activity values did not change, demonstrating the antibacterial agent's stability. The protocol proposed in this study is fast, simple, facile, and easily scalable for large-scale production. Using a green antibacterial agent and its loading with a one-step process without consuming chemicals or functionalizing the support makes the proposed method environmentally friendly.Article Citation - WoS: 50Citation - Scopus: 51A Facile Route To the Preparation of Antibacterial Polysulfone-Sulfonated Polyethersulfone Ultrafiltration Membranes Using a Cationic Surfactant Cetyltrimethylammonium Bromide(Elsevier, 2020) Cihanoğlu, Aydın; Alsoy Altınkaya, SacideCetyltrimethylammonium bromide (CTAB), a cationic surfactant, is known to have strong bactericidal potential. In this study, we report a facile approach for preparing CTAB-containing polysulfone-sulfonated polyethersulfone (PSF-SPES) based ultrafiltration membranes with antibacterial properties. The CTAB was added in gelation medium at three different concentrations and made an electrostatic interaction with SPES at the polymer/bath interface during phase inversion. The successful incorporation of the CTAB in the membrane structure was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The CTAB-containing membranes had higher contact angle, lower pure water permeability (PWP) and molecular weight cut-off than the pristine membrane. The membranes prepared at critical and above critical micelle concentration (CMC) of the CTAB showed excellent antibacterial activity on both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. On the other hand, the PWP of the membrane decreased from 93 +/- 1.6 to 39.3 +/- 3.2 L/m(2) h bar upon increasing the CTAB concentration from 10(-3) M (=CMC) to 10(-2) M, consequently, CMC was chosen as the optimal concentration. The membrane prepared at the CMC displayed almost 100% flux recoveries after dynamic bacteria filtration followed by simple rinsing with PBS solution. Leaching experiments continued up to 30 days demonstrated that 96% of the CTAB remained in this membrane. Furthermore, at the end of 1 month of storage in 1 M NaCl solution, no change was observed in the antibacterial activity of this membrane compared to fresh membrane. These findings emphasize the potential of the facile approach proposed in this study to develop antibacterial ultrafiltration membranes in a single step.Article Citation - WoS: 16Citation - Scopus: 16A High-Performance Acid-Resistant Polyaniline Based Ultrafiltration Membrane: Application in the Production of Aluminium Sulfate Powder From Alumina Sol(Elsevier, 2020) Güngörmüş, Elif; Alsoy Altınkaya, SacideIn this work, we report a new class of acid-resistant ultrafiltration membrane fabricated from polyaniline (PANI) based on its self-acid doping ability. The doped membrane was prepared by filtering the H2SO4 solution (pH = 0.55) through the PANI membrane at 2 bar. To critically assess the acid resistance, the resulting doped membrane was stored in H2SO4 solution (pH = 0.55) for one month. The chemical structure and separation performance of the membrane was not adversely affected by acid exposure. The membrane was also tested in realistic conditions through filtration of alumina sol synthesized in an extremely acidic H2SO4 solution. The results have shown that 99% recovery of the aluminium sulfate particles is possible with the doped PANI membrane as a result of the hydrophilic, relatively smooth, and antifouling surface created by acid doping. The membrane filtration did not change the size and size distribution of the particles in the sol. After filtration, concentrated particles were converted into powder form in 24 h at room temperature without using a dryer. The method proposed in this study is easy and robust and can be used to develop acid-resistant UF membranes not only for concentrating the alumina sol but also for recovering valuable compounds from acid-containing feeds.Article Citation - WoS: 51Citation - Scopus: 57Characterization of Waterborne Acrylic Based Paint Films and Measurement of Their Water Vapor Permeabilities(Elsevier, 2006) Topçuoğlu, Özge; Alsoy Altınkaya, Sacide; Balköse, DevrimRecently, production of waterborne coatings has increased significantly as a consequence of strict pollution regulations. Waterborne coatings are sensitive to humidity, thus, their barrier properties with respect to permeation of moisture needs to be determined. Among various coating constituents, binder represents the matrix structure and its amount relative to the amounts of pigments and fillers can significantly affect the structure, hence the barrier property of the coating. In this study, waterborne acrylic based paints applied as protective coating on interior and exterior wall of the buildings are studied. The paint samples formulated with four different binder contents by a commercial paint company are used in the experiments. We first determine unknown ingredients of the paint samples using different characterization tools and then investigate the effect of the binder content on the structure of the paint films. In addition, water vapor permeability of the paint films is measured using a permeation cell. Results show that the barrier property of the waterborne acrylic based paint films against humidity decreases with decreased binder content due to uneven distribution of the pigments, consequently, porous structure formation in the films.