TR Dizin İndeksli Yayınlar / TR Dizin Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7149
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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: 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 Citation - WoS: 2Tekstil Endüstrisinde Bütünleşik Membran Sistemi ile Su Geri Kazanımı ve Hibrit İleri Oksidasyon/membran Filtrasyonu ile Konsantrelerin Arıtımı ve Yönetimi(Pamukkale Üniversitesi, 2018) Kırıl Mert, Berna; Doğan, Esra C.; Balcı, Esin; Tilki, Yasemin M.; Aksu, Şeyda; Gören, Ayşegül Yağmur; Aydıner, CoşkunBu çalışmada, etkinliği bilinen UF/NFsıkı/TO membran kombinasyonu ile tekstil atıksularının arıtımının yanısıra %75-80 su geri kazanım oranı dahilinde oluşan membran konsantrelerinin, bütünleşik ileri oksidasyon prosesi (Fenton ve foto-Fenton (UVA-365–UVC-254))/batık UF sistemi ile daha önce belirlenen optimum işletme şartlarında oksidasyona tabi tutularak yönetimi gerçekleştirilmiştir. Yapılan deneysel çalışmalar sonucunda, UF/NFsıkı/TO membran konfigürasyonu ile arıtımı sonucunda oluşan konsantre akımlarının Fenton, foto-Fenton (UVA-365) ve (UVC-254) prosesleri/batık UF sistemi ile oksidasyonu sonrası, ardışık işletimli foto-Fenton (UVC-254)/UH050 hibrit prosesinin 9.88 H2O2/TOK ve 7.27 H 2 O 2 /Fe 2 + oranlarında, 44 L/m 2 .sa’lik süzüntü akısında %86 KOİ giderimi ile KOİ değeri 167 mg/L’ye ve %74.2 TOK giderimi ile TOK değeri 104 mg/L’ye kadar düşürülerek en iyi performans gösteren yenilikçi proses olduğu sonucuna varılmıştır. Oluşan membran konsantrelerin oksidasyonu sonrasında kalan konsantrenin tehlikelilik özellikleri, bertaraf/geri kazanım yöntemleri ve yeniden kullanım alternatifleri değerlendirildiğinde tekstil endüstrisi atıksularının foto-Fenton (UVA-365) ile arıtımı sonucunda oluşan konsantre haricinde diğer tüm konsantrelerin tehlikeli özelliğine sahip olduğu görülmüştür. Konsantrelerin bertaraf/geri kazanım yöntemleri ayrıntılı olarak değerlendirildiğinde, gerekli düzenlemeler (nem içeriği, susuzlaştırma, uygun debi ve/veya karışım oranları) yapıldığı takdirde bu konsantrelerin düzenli depolama, yakma ve merkezi atıksu arıtma sistemine verme gibi seçeneklerle bertaraf edilebileceği sonucuna varılmıştır.Article Citation - WoS: 4Citation - Scopus: 4PEG-peptide conjugate containing cathepsin B degradation unit as a doxorubicin carrier system(TUBITAK, 2018) Şentürk, Nesligül; Top, AybenA drug delivery system (DDS) containing a cathepsin B degradable sequence and pH-responsive histidines was prepared by methoxypolyethylene glycol and peptide conjugation. Doxorubicin was attached to the carrier system using amide linkage to give the final form of the DDS, denoted as mPEG-AT3-DOX. mPEG-AT3-DOX exhibited a bimodal size distribution at about 15 and 30 nm independent of pH, whereas the size of the control DDS containing no peptide sequence, mPEG-DOX, was measured as ∼ 15–20 nm. At the end of 72 h, % doxorubicin release from both of the DDSs was observed to be below 8.5 ± 3% in the absence of cathepsin B, and it increased to 17 ± 2% in the presence of cathepsin B for mPEG-AT3-DOX. Complete degradation of AT3 peptide within 3 h upon incubation with cathepsin B suggests that lower than expected doxorubicin release is likely due to the aggregation tendency of mPEG-AT3-DOX. Absolute IC50 values indicated that the cytotoxicity trend of the samples is in the order of free DOX ≥ mPEG-AT3-DOX >mPEG-DOX. Considering these results, PEG-peptide-doxorubicin conjugates can be promising candidates in cancer therapy if they are designed to have more pronounced pH-responsive behavior to increase the drug release rate.Article Citation - WoS: 9Citation - Scopus: 10Hydrogenation of Citral Over Ni and Ni-Sn Catalysts(TUBITAK, 2008) Aykaç, Hilal; Yılmaz, SelahattinLiquid phase citral hydrogenation over zeolite-supported monometallic Ni and bimetallic Ni-Sn catalysts was studied. The zeolite support materials were Na-Y, Na-mordenite, and clinoptilolite. Ni and Sn contents of the monometallic and bimetallic catalysts were 8.1-9.2 wt% and 0.46 wt%, respectively. The type of the zeolite support affected the activity and selectivity of the catalysts differently. The main product of the citral hydrogenation reaction was citronellal, for both monometallic (84.5% yield) and bimetallic (44.5% yield) catalysts. The addition of promoter increased the selectivity to unsaturated alcohols (geraniol+nerol), i.e. it changed from 0.9% to 6.3% over mordenite and from 0.9% to 2.1% over Na-Y-supported catalysts. Furthermore, activity of the Ni catalysts decreased while the quantity of acetal remained almost constant. Intimate contact between active metal, promoter, and support, and a catalyst with a high concentration of weak acid sites gave high selectivity to geraniol+nerol.Article Citation - WoS: 3Citation - Scopus: 3Hydrogenation of Citral Over Pt and Pt-Sn Catalysts(TUBITAK, 2008) Aykaç, Hilal; Yılmaz, SelahattinHydrogenation of citral on monometallic (Pt) and bimetallic (Pt-Sn) catalysts was investigated. It was found that the catalyst activities and product distributions were different over Na-Y and Clino supports. Among monometallic catalysts, Pt/Na-Y was more selective to citronellol (3.9%) and unsaturated alcohols, geraniol and nerol, (14.1%). Sn addition increased the catalyst activities. However, its effect on product distribution differed. Yield of geraniol+nerol changed from 5.1% to 19.7% over Clino. However, selectivity to unsaturated alcohols over Na-Y decreased when it was prepared as a bimetallic catalyst support. Unsaturated alcohol formation was favored when there was a metal support interaction over monometallic catalysts, and metal-promoter interaction over bimetallic catalyst.