Researcher:
Akgün, Işık Sena

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PhD Student

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Işık Sena

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Akgün

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Akgün, Işık Sena

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2019 - 201912020 - 20234

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    Supercritical fluid reactive deposition: a process intensification technique for synthesis of nanostructured materials
    (Elsevier, 2022) Eriş, Gamze; Uzunlar, Erdal; N/A; N/A; N/A; N/A; N/A; Department of Chemical and Biological Engineering; Yousefzadeh, Hamed; Akgün, Işık Sena; Barım, Şansım Bengisu; Sarı, Tarık Bercan; Bozbağ, Selmi Erim; Erkey, Can; Researcher; Researcher; Researcher; PhD Student; Researcher; Faculty Member; Department of Chemical and Biological Engineering; N/A; N/A; N/A; N/A; N/A; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); N/A; N/A; N/A; Graduate School of Sciences and Engineering; N/A; College of Engineering; N/A; N/A; N/A; N/A; N/A; 29633
    Supercritical fluid reactive deposition (SFRD) is a promising process intensification technique for synthesis of a wide variety of nanostructured materials. The enhanced mass transfer characteristics of supercritical fluids (SCFs) coupled with high solubilities of reducing gases in SCFs provide many advantages related to equipment size and time minimization over conventional techniques. Among SCFs, the emphasis has been placed on supercritical CO2 (scCO(2)) which is non-toxic, cheap and leaves no residue on the treated medium. Moreover, in SFRD, multiple processes such as dissolution, adsorption, reaction, and purification are combined in a single piece of equipment which is an excellent example of process integration for process intensification. In this review, the fundamental thermodynamic and kinetic aspects of the technology are described in detail. The studies in the literature on synthesis of a wide variety of nanostructured materials including supported nanoparticles, films, and ion-exchanged zeolites by SFRD are reviewed and summarized. The applications of these materials as catalysts and sensors are described. The review hopes to lead to further studies on further development of this technology for a wide variety of applications.
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    Enteric coating of drug loaded aerogel particles in a wurster fluidized bed and its effect on release behaviour
    (Editions de Sante, 2023) Ulker, Zeynep; Demir, Enis; Işık, Murat; Ekmekçiyan, Nadin; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; N/A; N/A; N/A; Erkey, Can; Şenses, Erkan; Akgün, Işık Sena; Darvishi, Saeid; Karaz, Selcan; Faculty Member; Faculty Member; PhD Student; PhD Student; Master Student; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); College of Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 29633; 280298; N/A; N/A; N/A
    Ibuprofen loaded and unloaded alginate aerogel particles were successfully coated with methacrylic acid-ethyl acrylate copolymer in a Wurster fluidized bed. Pores of both aerogels were well-preserved during the coating process. Effects of drug loading, polymer rheology, and atomizing pressure on coating thickness and coating layer surface morphology were investigated. Coatings were conducted at circulatory particle motion regime. Due to low weight of unloaded aerogels, this regime was achieved at lower air flow rates than ibuprofen loaded aerogels. Coatings of ibuprofen loaded aerogels were conducted between 1.3 and 1.5 bar atomizing pressures and at 60 °C. Unloaded aerogels were coated at a constant and high atomizing pressure of 1.7 bar and at 60 °C. At this condition, coating thickness of unloaded aerogels increased linearly from 25.6 μm to 53.4 μm with increasing coating time from 10 to 50 min. For ibuprofen loaded aerogels, coating thickness increased non-linearly from 15.9 μm to 84.1 μm with increasing coating time from 10 to 180 min. Ibuprofen release from aerogels in acidic medium was prevented via coating. In the basic medium, the fastest release was obtained from uncoated aerogels and 57% of ibuprofen was released in 30 min while 44% of crystalline ibuprofen dissolved at the same time. The slowest release rate was achieved via coating and 13% of the drug was released from coated aerogels in 30 min. © 2023 Elsevier B.V.
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    Protective coating of highly porous alginate aerogel particles in a Wurster fluidized bed
    (Elsevier, 2022) Demir, Enis; Işık, Murat; Ekmekciyan, Nadin; N/A; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Akgün, Işık Sena; Şenses, Erkan; Erkey, Can; PhD Student; Faculty Member; Faculty Member; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; 280298; 29633
    Alginate aerogel particles were successfully coated with a copovidone and hydroxypropyl cellulose based polymer in a Wurster fluidized bed. The results indicate that the pores of aerogels were not damaged during the process. Several sets of experiments were conducted at three different temperatures and atomizing air pressures. Coating time for all the runs ranged from 5 min to 40 min and the coating thickness ranged from 12.4 +/- 4.6 mu m to 170.6 +/- 43.3 mu m.Changing bed temperature led to significant changes in coating thickness whereas both bed temperature and atomizing pressure affected coating layer surface morphology. The smoothest coating layer surface and the highest coating efficiency which was 69.2 +/- 0.4% were achieved at 50 degrees C with 1.7 bar atomizing pressure. At this condition, the coating layer thickness increased linearly with coating time.(c) 2022 Elsevier B.V. All rights reserved.
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    Fluidization regimes for alginate aerogel particles in a laboratory scale Wurster fluidized bed
    (Elsevier, 2021) N/A; Department of Chemical and Biological Engineering; Akgün, Işık Sena; Erkey, Can; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; College of Engineering; N/A; 29633
    Fluidization regimes for alginate aerogel particles with two different particle sizes were characterized in a labo-ratory scale Wurster fluidized bed both in the annular zone and the tube zone. For both particle sizes, minimum fluidization and bubbling regimes were observed in both of the zones whereas pneumatic regimes existed only in the tube zone. Moreover, a new regime which was horizontal circular motion was identified for large particles in the tube zone. There existed two other regimes in the bed which were turbulent and circulatory particle motion regimes. All fluidization regimes were mapped on Kunii and Levenspiel diagrams. Circulatory particle motion re-gime was given on these diagrams for the first time. Furthermore, effects of particle size, batch volume, Wurster tube size, perforated plate geometry and partition gap height on the boundaries of each fluidization regime were investigated by measuring superficial air velocities at the onset and the end of each regime.& nbsp; (c) 2021 Elsevier B.V. All rights reserved.
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    PublicationOpen Access
    Investigation of hydrodynamic behavior of alginate aerogel particles in a laboratory scale Wurster fluidized bed
    (Multidisciplinary Digital Publishing Institute (MDPI), 2019) Department of Chemical and Biological Engineering; Erkey, Can; Akgün, Işık Sena; Faculty Member; Researcher; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; 29633; N/A
    The effects of design and operating parameters on the superficial velocity at the onset of circulatory motion and the residence time of alginate aerogel particles in a laboratory scale Wurster fluidized bed were investigated. Several sets of experiments were conducted by varying Wurster tube diameter, Wurster tube length, batch volume and partition gap height. The superficial velocities for Wurster tube with 10 cm diameter were lower than the tube with 8 cm diameter. Superficial velocities increased with increasing batch volume and partition gap height. Moreover, increasing batch volume and partition gap height led to a decrease in the particle residence time in the Wurster tube. The results showed that there is an upper limit for each parameter in order to obtain a circulatory motion of the particles. It was found that the partition gap height should be 2 cm for proper particle circulation. Maximum batch volume for the tube with 10 cm diameter was found as 500 mL whereas maximum batch volume was 250 mL for the tube with 8 cm diameter. The fluidization behavior of the aerogel particles investigated in this study could be described by the general fluidization diagrams in the literature.