Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Article Citation - Scopus: 2A Comparative Assessment for Efficient Oleuropein Extraction From Olive Leaf (olea Europaea L. Folium)(Murat Yakar, 2023) Recepoğlu, Yaşar Kemal; Gümüşbulut, Gülin; Yüksel Özşen, AslıSince oleuropein has long been known in the health sector and is abundant directly in our country as the fourth largest olive producer, oleuropein, the predominant phenolic ingredient in olive leaves, was recovered in this study using Soxhlet extraction. The effects of different solvent types (acetonitrile, ethanol, methanol, and water), extraction period (4 cycles, 4 h, and 8 h), particle size (250-500 µm and 900-2000 µm), and pretreatment of olive leaves on the yield of oleuropein were examined to determine the maximum yield. A greater oleuropein yield was obtained when the particle size of olive leaves utilized for extraction was lowered. Furthermore, aqueous solvents revealed a higher yield of oleuropein than pure solvents and prolonging the extraction duration resulted in a significant increase in the amount of oleuropein extracted. On the other hand, pretreatment of olive leaves resulted in a reduction in oleuropein output. As a result, with 36% extraction efficiency in terms of olive leaf conversion, the highest oleuropein extraction yield was obtained as 13.35 mg g-1 dry leaf for 8 h of extraction time using olive leaves with a particle size of 250-500 µm and an 80% methanol solution as solvent. © Author(s) 2023.Article Citation - WoS: 3Citation - Scopus: 4Photocatalytic Degradation of Aquatic Organic Pollutants With Zn- and Zr-Based Metalorganic Frameworks: Zif-8 and Uio-66(TÜBİTAK - Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, 2022) Çalık, Fatma Defne; Erdoğan, Bilgesu; Yılmaz, Esra; Saygı, Gizem; Çakıcıoğlu-Özkan, FehimeWater treatment has been an essential issue with the increasing population over 40 years. Researchers center on the major organic pollutants, such as dyes, pesticides, and pharmaceutical products. Photocatalytic degradation is one of the promising methods for aquatic organic pollutant treatment. Over the years, scientists have been working on developments for photocatalysts to enhance their pollutant degradation performances. From the reviewed studies, it is seen that properties like surface area, chemical, mechanical, and thermal stability, and uniform distribution of active sites are crucial, and an increase in these properties provides better degradation efficiency. In this sense, metal-organic frameworks as photocatalysts can be considered more advantageous. This study focuses on the organic aquatic pollutant degradation studies by using well-known MOFs like ZIF-8 and UiO-66 photocatalysts. Mainly the organic dye (RhB, MB, MO, etc.) degradation efficiencies of ZIF-8 and UiO-66 have been achieved to 100%. Recently, the degradation capacities of various pharmaceuticals such as diazinon, acetaminophen, levofloxacin, and sulfamethoxazole have also been investigated. According to the reviewed studies, ZIF-8 and UiO-66 can be considered remarkable photocatalysts for the degradation of organic pollutants.Article Citation - WoS: 4Citation - Scopus: 5Co2 Absorption Into Primary and Secondary Amine Aqueous Solutions With and Without Copper Ions in a Bubble Column(TÜBİTAK - Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, 2022) Yousefzadeh, Hamed; Güler, Cansu; Erkey, Can; Uzunlar, ErdalChemical absorption of CO2 into aqueous amine solutions using a nonstirred bubble column was experimentally investigated. The performance of CO2 absorption of four different primary and secondary amines including monoethanolamine (MEA), piperazine (PZ), 2-piperidineethanol (2PE), and homopiperazine (HPZ) were compared. The effects of initial concentration of amine, the inlet mole fraction of CO2, and solution temperature on the rate of CO2 absorption and CO2 loading (mol CO2/mol amine) were studied in the range of 0.02–1 M, 0.10–0.15, and 25–40 °C, respectively. The effect of the presence of copper ions in the amine solution on CO2 loading was also studied. By comparison of the breakthrough curves of the amines at different operational conditions, it was revealed that the shortest and longest time for the appearance of the breakthrough point was observed for MEA and HPZ solutions, respectively. CO2 loading of MEA, 2PE, PZ, and HPZ aqueous solutions at 25 °C, 0.2 M of initial concentration of amine, and 0.15 of inlet mole fraction of CO2 were 1.06, 1.14, 1.13, and 1.18 mol CO2/mol amine, respectively. By decreasing the inlet mole fraction of CO2 from 0.15 to 0.10, CO2 loading slightly decreased. As the initial concentration of amine and temperature decreased, CO2 loading increased. Also, the presence of copper ions in the absorbent solution resulted in a decrease in the CO2 loading of MEA and HPZ aqueous solutions. In case of PZ and 2PE amines, adding copper ions led to precipitation even at low copper ion concentrations.Article Citation - WoS: 1Citation - Scopus: 1Selective Catalytic Hydrogenation of Cellulose Into Sorbitol With Ru-Based Catalysts(TÜBİTAK, 2022) Orak, Ceren; Sapmaz, Aycan; Yüksel, AslıSorbitol is one of the platform chemicals and can be produced from various renewable and sustainable sources via different processes. Hydrothermal liquefaction is an effective and promising approach to produce sorbitol, since the subcritical reaction media and appropriate catalysts provide a selective production of platform chemicals. In this study, sorbitol was produced from different renewable sources (cellulose and glucose) in the presence of Ru-based catalysts (Ru/SiO2, Ru/AC, Ru/SBA-15, and Ru/SBA-15-SO3) under subcritical conditions. The highest cellulose conversion was achieved as 90% in the presence of Ru/SBA-15-SO3 for 1 h of reaction duration. The highest sorbitol yield (%) by hydrothermal liquefaction of cellulose was obtained as 6.2% by using Ru/AC for 1 h of reaction duration. A total of 99.9% of glucose conversion was achieved in the presence of all catalysts. The highest sorbitol yield (%) by hydrothermal liquefaction of glucose was found as 3.8% for 1 h of reaction duration. Owing to the results of GC-MS analysis, the intermediate products were identified, and, thus, a reaction pathway was proposed.Article Citation - WoS: 5Citation - Scopus: 5Evaluation of Liposomal and Microbubbles Mediated Delivery of Doxorubicin in Two-Dimensional (2d) and Three-Dimensional (3d) Models for Breast Cancer(Galenos Publishing House, 2021) Aydın,M.; Özdemir,E.; Altun,Z.; Kılıç,S.; Aktaş,S.Objective: Liposomal cancer treatment strategies are useful in removing the side effects that were the main concern in recent years. In this study, we prepared microbubble (MBs) conjugated with DOX-loaded liposomes (DOX-loaded MBs) and investigated their effectiveness in in vitro breast cancer cells in two dimensions (2D) and three dimensions (3D). Materials and Methods: With this aim, breast cancer cells with different features (4T1, MDA-MB231, MCF-7) were growth in 2D and 3D dimensions. The cytotoxic and cell death effects under different conditions, durations and doses were evaluated with WST-1, trypan-blue, colony counts. Apoptotic effects were investigated with flow cytometric Annexin-V-PI and immunohistochemical (Ki-67, caspase 3, 8, 9) methods. Results: After free DOX and LipoDOX were applied, the proliferation index of three cell lines reduced. Intrinsic and extrinsic apoptotic pathways were activated in both 2D and 3D models. However, this effect was observed at lower levels in the 3D model due to the difficulty of diffusion of DOX into the spheroids. Additionally, the suitability of the 3D model for breast cancer cells was supported by formation of ductus-like structures and spheroids. Cell deaths were not observed significantly with the DOX-loaded microbubbles due to rising of MBs to the surface and not reaching spheroids held in matrigel of 3D model. Conclusion: DOX and LipoDOX showed anti-proliferative and apoptosis-inducing effects in breast cancer cells. However, these effects indicated variability depending on the cell lines and 2D or 3D model types. ©Copyright 2021 by the the Turkish Federation of Breast Diseases Societies.Article Citation - WoS: 1Citation - Scopus: 1Potansiyel Doksorubisin Taşıyıcı Sistemi Olarak Peg-endozom Parçalayıcı Peptit Konjugatının Değerlendirilmesi(Gazi Üniversitesi, 2020) Şen, Selin; Top, AybenIn this study, it was aimed to develop a doxorubicin (DOX) carrier system based on a PEGylated TAT-derived cell penetrating peptide (G(2)RQR(3)QR(3)G(2)S) and to investigate drug release, self-assembly and stability properties of the carrier system. In the preparation of the drug delivery system, denoted as mPEG-peptide-oxime-DOX, methoxypolyethylene glycol (mPEG) with M-n=1900 Da was used. DOX was attached to the mPEG-peptide carrier system via acid cleavable oxime bond. Control drug delivery system, lack of the peptide (mPEG-oxime-DOX) was also synthesized to assess the effect of the peptide on the physicochemical and DOX release properties of the carrier system. mPEG-oxime-DOX exhibited a pH programmed DOX release with respective % DOX release values of similar to 68% and similar to 28% at pH 5.0 and at pH 7.4 at the end of 54 h. For the mPEG-peptide-oxime-DOX, on the other hand, quite low DOX release (similar to 10-15 %) was observed for both pH values suggesting possible interactions between DOX and the peptide. Initial median size value (D50) of the mPEG-oxime-DOX was measured as similar to 24 nm, independent of pH. However, for the mPEG-peptide-oxime-DOX, quite lower D50 values (similar to 3 nm and similar to 6 nm at pH 5.0 and pH 7.4, respectively) were obtained due to the repulsions between the arginines in the peptide sequence. Sizes of both drug delivery systems, tended to increase upon incubation at physiological conditions for 1 day suggesting that longer PEG chains should be used to enhance the stability of the mPEG-peptide-oxime-DOX and mPEG-oximeDOX systems.Article Citation - WoS: 11Citation - Scopus: 13Effect of Cnt Incorporation on Pan/Ppy Nanofibers Synthesized by Electrospinning Method(TÜBİTAK, 2020) İnce Yardımcı, Atike; Tanoğlu, Metin; Yılmaz, Selahattin; Selamet, YusufIn this study, carbon nanotubes (CNTs) added polyacrylonitrile/polypyrrole (PAN/PPy) electrospun nanofibers were produced. Average diameters of the nanofibers were measured as 268 and 153 nm for 10 and 25 wt% of PPy contents, respectively. A relatively higher strain to failure values (23.3%) were observed for the low PPy content. When as-grown CNTs (1 and 4 wt%) were added into the PAN/PPy blends, disordered nanofibers were observed to form within the microstructure. To improve the interfacial properties of CNTs/PAN/PPy composites, CNTs were functionalized with H2SO4/HNO3/HCl solution. The functionalized CNTs were well dispersed within the nanofibers and aligned along the direction of nanofibers. Therefore, beads formation on nanofibers decreased. The impedance of the nanofibers was found to decrease with the PPy content and CNT addition. These nanofibers had a great potential to be used as an electrochemical actuator or a tissue engineering scaffold.Article Effect of Temperature on Stability of Lipid Microbubbles(Turkish Chemical Society, 2019) Kılıç, SevgiThe effect of temperature on stability of lipid microbubble shell containing polyethyleneoxide-40-stearate (PEG40St) as emulsifier was investigated. Microbubbles at 4 °C were subjected to different temperatures up to 48 ºC (down-to-up) and it was found that both the number and the size of microbubbles remained unchanged in the population up to a certain time, so called “onset time”. The onset time was about 6 hours at 10 °C, 2 hours at 20 °C and shorter at elevated temperatures, exhibiting an exponential decrease with increasing temperature. Once the onset time was reached, the number of microbubbles started to decrease and the average size of the population started to increase. Observation of single microbubbles on a constant temperature heating stage exhibited that each microbubble had its own onset time, with the smaller microbubbles vanishing earlier than the larger ones. The Langmuir monolayer studies showed that hydration degree of the emulsifier PEG chains decreased with temperature, causing them go through conformational changes and subsequently destabilization of the shell. By subjecting the freshly produced microbubbles directly to the desired temperatures in up-to-down fashion, more stable microbubbles were able to be produced, with their onset time increased 40% at 10 °C to 500% at 38 °C. Overall, the results suggest that the new strategies need to be developed to control the collapse process in the microbubble shell resulting from the conformational changes in the PEG chains of the emulsifier for the design of more stable microbubbles. © 2019, Turkish Chemical Society. All rights reserved.Article Citation - Scopus: 1Synthesis of Stable Nano Calcite(Turkish Chemical Society, 2018) Kılıç, SevgiSynthesis of calcium carbonate (CaCO3) particles in the presence of a population of carbon dioxide (CO2) bubbles was investigated in the calcium hydroxide (Ca(OH)2) solution, which is a natural stabilizer for CaCO3. Possible chemical speciation reactions were presented for an inorganic synthesis of hollow nano-CaCO3 particles. In the progress of CaCO3 synthesis, some of the particles started to dissolve at their edges and turned into hollow nano-CaCO3 particles. Some of the pores closed at the end of crystallization as a result of dissolution-recrystallization mechanism. Hollow nano-CaCO3 particles with sizes of about 300 nm were synthesized with a narrow size distribution. It was concluded that the hollow nano-CaCO3 particles could be advantageous due to lower weights and higher surface areas.Article Citation - Scopus: 7Binder Effect on Electrochemical Performance of Zinc Electrodes for Nickel-Zinc Batteries(Turkish Chemical Society, 2018) Ebil, Özgenç; Cihanoğlu, GizemPolyethylene glycol (PEG) and polyvinyl alcohol (PVA) were used as a zinc electrode binder at different concentrations to enhance the electrochemical behavior of zinc electrodes for nickel-zinc (NiZn) batteries. ZnO powders synthesized by mechanochemical and hydrothermal precipitation methods were mixed with lead oxide, calcium hydroxide and binder to prepare zinc electrodes in pouch cell NiZn batteries. Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) analysis reveal that initial morphology of zinc electrode changes drastically regardless of the binder type and its loading after charge/discharge process, and even the charge/discharge process is not complete. The results show that the presence of PEG causes better discharge capacity compared to that of PVA as a binder. Zinc electrode prepared using commercial ZnO powder and 3 wt.% PEG gives the optimum discharge capability, with a specific capacity of approximately 311 mAhg-1, while zinc electrodes prepared using ZnO powder synthesized from ZnCl2 and Zn(NO3)2.6H2O and 6 wt.% PEG exhibit high specific energy of 255 and 275 mAhg-1, respectively. The results suggest a relationship between binder loading and battery capacity, but in-situ analysis of microstructural evolution of zinc electrode during charge/discharge process is needed to confirm this relationship.