Yazar "Cetin, Ali Emrah" seçeneğine göre listele

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    Fabrication of ZIF-8 decorated copper doped TiO2 nanocomposite at low ZIF-8 loading for solar energy applications
    (Elsevier, 2021) Yurtsever, Husnu Arda; Cetin, Ali Emrah
    The effects of crystallization time and amount of Zeolitic Imidazolate Framework-8 (ZIF-8) on the photocatalytic activity of ZIF-8 decorated copper (Cu) doped titania (TiO2) (ZIF-8/Cu-TiO2) powders were investigated in this study. The formation of nanocomposite structure of ZIF-8 crystals grown over the surface of core Cu-TiO2 particles containing heterojunction sites was observed at low ZIF-8 level. Powders containing ZIF-8 in the 5-46% range (weight basis) were synthesized and their activities in the photocatalytic degradation of an organic dye molecule were evaluated. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (ATR-FTIR), thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HR-TEM) analyses indicated that ZIF-8/Cu-TiO2 nanocomposite can be prepared at low levels of ZIF-8. HR-TEM images of 46% ZIF-8/Cu-TiO2 showed that Cu-TiO2 particles act as a core and ZIF-8 crystals grow over the surface of Cu-TiO2 particles during crystal growth and Cu-TiO2 particles were almost completely covered with ZIF-8 crystals. Photocatalytic activity increased with decreasing ZIF-8 level which was attributed to the formation of heterojunctions due to partial coverage of TiO2 surface. The 1st order reaction rate constant of ZIF-8/Cu-TiO2 nanocomposite containing 5% ZIF-8 was found to be 4 and 1.4 times that of bare ZIF-8 and CuTiO2, respectively. Partial coverage of TiO2 surface with ZIF-8 crystals lead to the formation of light exposed ZIF8/Cu-TiO2 heterojunction sites for the enhanced degradation of the dye molecule. The presence of ZIF-8 in the nanocomposite also increased the adsorption of the organic dye by the interaction with open Zn2+ metal sites of ZIF-8 on the nanocomposite surface. This study revealed that ZIF-8/Cu-TiO2 nanocomposites could be prepared at low ZIF-8 levels and short growth times with higher photocatalytic activities than their constituents and nanocomposites prepared at higher ZIF-8 levels and longer growth times.
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    Fatty acids, triglycerides, tocol, and sterol contents of oils of some Moringa seed varieties
    (Innovhub Ssi-Area Ssog, 2023) Kola, Osman; Gokalp, Smeyye; Parildi, Erva; Ozkul, Neslihan; Akkaya, Murat Reis; Cetin, Ali Emrah
    Three moringa oliefera varieties (MOMAX 3, ODC and PKM-1) seeds were used in this study. The oil was extracted from the seeds of ODC, PKM1 and MOMAX 3 moringa varieties by cold press (CP) and the solvent extraction (SE) method. Fatty acids, triglycerides, tocols (tocopherols and tocotrienols) and sterol contents of moringa seed oils obtained by two different methods were determined and compared with one another. The crude oil yield was between 26.46 - 28.19% in solvent extraction and 24.20 - 26.30% in the cold press method. It was determined that the main fatty acid in moringa seed oils (ODC, PKM1 and MOMAX 3) was Oleic acid (63.31 - 70.04%). Other dominant fatty acids were determined to be palmitic acid (16:0) (5.59-7.26%), stearic acid (18:0) (5.37-5.89%), oleic acid (18:1 n9) (%63.31-70.04), arachidic acid (20:0) (2.67 - 3.71 %) and behenic acid (22:0) (3.82 5.73%). It was determined that the main triglyceride in moringa seed oils was triolein (000; 35.63 - 36.50%), the main sterol was [3-Sitosterol (39.04 - 42.11 %) and the main tocopherol was a-tocopherol (15.88 -18.91 pg/g).
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    Pilot-scale hydrogen generation from the hydrolysis of black aluminum dross without any catalyst
    (Elsevier Sci Ltd, 2022) Kale, Mehmet; Yilmaz, Ibrahim Halil; Kaya, Abdulaziz; Cetin, Ali Emrah; Soylemez, Mehmet Sait
    This study presents a sustainable method for the production of hydrogen gas without adding any catalyst from the hydrolysis of black Al dross. A pilot-scale experimental setup consisting of a reactor, a condenser, and control and measurement devices was constructed to perform chemical reactions and physical measurements. The dross used in experiments was not activated by any process and can be found in facilities (Al production plants or die casting factories) with a grain size lower than 400 mu m. The chemical composition revealed by XRF showed that the black dross contained 41.96% Al. Major and minor crystalline phases present in the sample were detected by XRD. A set of experiments was performed to investigate the effects of gravimetric dross to water ratio, pH value, initial water temperature, the pressure of the reaction mixture in time for H-2 synthesis. 120 L of gas were maximally produced after reacting 1 kg of Al dross with 2 kg of hot tap water at 100 degrees C. The H-2 purity of the gas mixture and the calorific value of the mixture were respectively measured by gas chromatography and gas calorimeter as 93.24% and 2375 kcal/m(3). After hydrolysis of the Al dross, XRD, SEM, and EDX analyses revealed the formation of hydrolysis products and their morphology. This showed that the resultant mixture tends to become harmless and can be used for various fields of the industry as a by-product.
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    Preparation and characterization of hydroxyapatite reinforced polymeric scaffolds
    (National Institute of Science Communication and Information Resources-NISCAIR, 2025) Firata, Duygu Doga; Ersoz, Su Turku; Burcu Alp, Fatma; Cetin, Ali Emrah; Ciftcioglu, Muhsin
    Porous HA reinforced PLA/PCL scaffolds with polymer volume percentages in the 7.0-7.6 range have been prepared by solvent-casting/salt leaching technique. The scaffolds have been characterized by conducting gravimetric measurements, FTIR analysis, TGA, X-ray diffraction analysis, compression tests, cell viability tests, and thermal and hydrolytic degradation tests in order to investigate the effect of PLA/PCL, PLA/HA, PCL/HA and PLA/PCL/HA blending on scaffold properties. Porosity of the scaffolds has been determined to be in the 83-92 percent range. The scaffold porosity has decreased with HA content. The water absorption of the scaffolds has been found to be in between 400 and 750%. The yield strength and the elastic modulus of the scaffolds have been determined to be in the 0.001-0.02 and 5.6-10.6 MPa ranges, respectively. The yield strength of the scaffolds has increased by both PCL and HA contents whereas elastic modulus has increased with PCL content but has decreased with HA content. Mechanical test results have indicated that the addition of HA has increased the strength of the scaffolds while decreasing their flexibility. The activation energies for the thermal degradation of the scaffolds have been determined to be in the 130-398 kJ/mol range and have been shown to be a function of PCL, PLA, and HA content. The hydrolytic degradation behavior of the scaffolds in acetate buffer solutions (pH=4.5) during 127 days and XRD analysis have indicated that the hydrolytic degradation occurring in the amorphous part of the surface film has been diffusion-controlled. The diffusion coefficients of the degradation products in the scaffolds have been estimated to be in the 1.21-4.95x10(-13) m(2)/s range. Cell viability test results have indicated that the composition of the composite scaffold structure has played a determining role in the prepared scaffolds.