Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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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: 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: 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.