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Öğe Changes in N, K, and Fatty Acid Composition of Black Cumin Seeds Affected by Nitrogen Doses under Supplemental Potassium Application(Hindawi Ltd, 2017) Aytac, Zehra; Gulmezoglu, Nurdilek; Saglam, Tugce; Kulan, Engin Gokhan; Selengil, Ugur; Hoşgün, Halit LeventThis study was carried out to determine the efficiency of nitrogen (N) doses (0, 30, 60, and 90 kg N ha(-1)) under supplemental potassium (K) application (50 kg K-2 O ha(-1)) on black cumin in 2011 and 2012. The results showed that increased N levels resulted in increasing seed yield and N and K contents in seed, while oil content decreased. The seed yield and oil yield were peaked at the doses of 60 kg N ha(-1) and 50 kg K ha(-1). An increase in N doses caused a reduction in oil content regardless of K supply. Saturated fatty acids and oleic acid were slightly increased by K application, while minor changes in linoleic acid were detected. It was concluded that 60 kg N ha(-1) with supplemental K application should be advised for enhancement in seed yield, oil yield, and N and K contents in seeds of black cumin without significant changes in fatty acid composition.Öğe Characterization studies of heat-treated halloysite nanotubes(Springer International Publishing Ag, 2020) Aytekin, M. Turkay; Hoşgün, Halit LeventThe halloysite nanotubes (HNTs), subjected to different temperatures in the range 250-1000 degrees C, were investigated at room temperature. The materials have been prepared in various times (2, 4, 6 h) at different temperatures (250, 450, 600, and 1000 degrees C) and heating rates (5, 10, 20 degrees C/min). Morphology, structural and physical properties of raw, and thermally treated HNTs were systematically analyzed by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), the nitrogen adsorption-desorption isotherm (BET), as well as Fourier transform infrared (FT-IR) spectroscopy. The XRD patterns indicate that the crystal structure of halloysite is stable up to 450 degrees C. The scanning electron micrograph images of the Halloysite nanotubes showed that the unheated and heated halloysite nanotubes possessed typical tubular shapes. Tubular shapes were observed even at 1000 degrees C. Fourier transform infrared spectroscopy was also used to examine the variations of chemical structures. The Fourier transform infrared spectra of unheated and thermally treated halloysite nanotubes showed the presence of hydroxyl stretching and bending vibration frequencies in the samples. In this study, the structural properties of natural halloysite nanotubes are comprehensively reviewed in terms of given temperature, heating rate, and time. It is thought that the obtained results will guide the design and preparation of halloysite-based new structural and functional materials which can be applicable in various fields.Öğe Effect of molar ratio of PVP/AgNO3 and molecular weight of PVP on the synthesis of silver nanowires(Old City Publishing, 2017) Sağlam, Gökçenur; Borazan, I.; Hoşgün, Halit Levent; Demir, A.; Bedeloğlu, AyşeIn this paper, the effect of different parameters including the molar ratio of PVP/AgNO3 and the molecular weight of PVP on the silver nanowires synthesized by polyol method was investigated. The polyol method was performed in the presence of glycerol to obtain silver nanowires with optimum shape and therefore, experiments were repeated using different molecular weights of PVP and aspect ratios of PVP/AgNO3. Optical, structural and morphological characterizations were carried out to understand the effect of parameters on formation of silver nanowires. The results indicated that both molar ratio and molecular weight have influence on silver nanowire synthesis reaction. Silver nanowires with desired shape and high aspect ratio were obtained when PVP with low molecular weight and low molar ratio of PVP/AgNO3 were used. ©2017 Old City Publishing, Inc.Öğe Esterification of acetic acid in the presence of sulfated clinoptilolite: a model study of upgrading of pyrolysis bio-oil(Taylor & Francis Inc, 2021) Hoşgün, Halit LeventIn this study, the esterification reaction of acetic acid with n-propyl alcohol was studied on a sulfated zeolite catalyst to improve the bio-oil obtained by pyrolysis of lignocellulosic biomass. Temperature (323-353 K), sulfuric acid concentration (1-3 M) and time (1-4 hours) were selected as parameters in the preparation of sulfuric acid-modified clinoptilolite samples. Sulfated zeolites samples are characterized by XRF, XRD, and N(2)adsorption/desorption techniques. It was observed that the zeolites treated with sulfuric acid retained their crystal structures, decreased surface areas, and changed SiO2/Al(2)O(3)ratios. Samples modified with sulfuric acid are more effective in the esterification reaction than unmodified zeolite. The increase in sulfuric acid concentration and temperature in the modification process increased the conversion of acetic acid in the esterification reaction. The highest acetic acid conversion (63.8%) was obtained with zeolite treated at 323 K temperature, 3 M sulfuric acid for 1 hour.Öğe Hydrothermal synthesis and characterization of vanadium-doped titanium dioxide nanotubes(Springer, 2020) Aydin, M. Turkay Aytekin; Hoşgün, Halit LeventUndoped and vanadium (V)-doped titanium dioxide nanotubes (TNTs and VTNTs, respectively) were synthesized by hydrothermal method for biological applications. The fabricated nanotubes were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, nitrogen adsorption-desorption isotherms, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The XRD and vibrational spectra results showed as-prepared nanotubes were complete anatase phase. The characterization of the morphology of the as-obtained nanotubes reveals that the samples are tubular in shape and the starting spherical titanium particles were fully transformed into a tubular material. The TEM and SEM results are in good agreement with XRD, FT-IR, and Raman analysis. The purpose of this study is to produce and characterize the vanadium-doped titanium dioxide nanotubes, such that this material can be employed for biomedical applications. TEM and SEM findings cleared that vanadium doping does not affect significantly the structure of titanium dioxide nanotubes which are uniform and compact.Öğe KINETICS OF THE ESTERIFICATION OF PROPIONIC ACID WITH ISOBUTYL ALCOHOL OVER AMBERLYST 36 AND AMBERLYST 70(2018) Çıtak, Alime; Hoşgün, Halit LeventThe esterification of propionic acid with isobutyl alcohol has been studied in a batch reactor in the presence of Amberlyst 36 and Amberlyst 70 catalysts. Reaction parameters applied in this study are speed of agitation (500-1000 rpm), particle size of catalyst (400-600 µm, 600+ µm), temperature (318-348 K) and catalyst loading (4-12 g-dry resin/L). A pseudo-homogeneous kinetic model was derived and all thermodynamic and kinetic parameters were calculated. Forward reaction rate constant for Amberlyst 36 and Amberlyst 70 determined as follows: $ k1 = 160171 exp(-56689/RT) (L mol-1 min-1)$ $ k1 = 293314 exp(-57292/RT) (L mol-1 min-1)$ In a comparison of the two catalysts used in this study, experimental results showed that Amberlyst 70 is more effective than Amberlyst 36.Öğe MAGNESIUM HYDROXIDE RECOVERY FROM MAGNESIA WASTE BY CALCINATIONS AND HYDRATION PROCESSES(Oficyna Wydawnicza Politechniki Wroclawskiej, 2015) Kurama, Haldun; Hoşgün, Halit LeventIn this study, hydration behavior of the magnesia waste, supplied from the electrostatic bag house of the sintering unit of MAS Company, Eskisehir-Turkey was studied to find out re-usability of the material as a source of magnesium hydroxide (Mg(OH)(2)) production. According to chemical and crystalline phase analyses, MgO content of the sample was determined as 49.9 wt% and consists of mainly raw magnesite (MgCO3), sintered magnesia-periclase (MgO) and small amount of serpentine (lizardite) phases. In hydration process, the reactivity of magnesium oxide determines the rate and extent of hydration of the sample. Therefore, the waste samples both calcined and uncalcined forms were hydrated in water and the efficiencies were compared according to sample source. The hydration experiments were carried out at temperatures ranging from 30 degrees C and 80 degrees C to evaluate the influence of temperature on particle morphology and surface areas of the products. The efficiency of the hydration was evaluated by using thermogravimetric (TG) and scanning electron microscopy (SEM) analyses. The test results suggest that the magnesia waste could be used as a source material for production of magnesium hydroxide.Öğe Magnesium hydroxide recovery from magnesia waste by leaching and precipitation process(2013) Kurama, H.; Ayvazoğlu Yüksel, G.; Hoşgün, Halit LeventThe objective of the study is to determine the recyclability of magnesia waste as a relatively pure magnesium hydroxide. In previous study, it was found that magnesium can readily soluble in HCl solution and both temperature difference and the concentration of solution strongly affect the reaction rates and the solution compositions. Therefore, present study is devoted to the precipitation of Mg(OH)2 from MgCl2 solution conducted with using NaOH and Ca(OH)2. The waste sample at first leached by using HCl and the leached solution is subsequently submitted to series of neutralizing steps under controlled pH to remove the acid soluble impurities such as Si, Fe, etc present in solution together with dissolved Mg. The importance of solution pH and type of the precipitation reactive used in precipitation stages were tested and discussed to find out their effect on the separation process. The test results showed that Mg(OH)2 can be obtained with a impurities level less than 2 %.Öğe Synthesis 5-hydroxymethylfurfural (5-HMF) from fructose over cetyl trimethylammonium bromide-directed mesoporous alumina catalyst: effect of cetyl trimethylammonium bromide amount and calcination temperature(Springer, 2020) Hoşgün, Halit Levent; Türe, Ayşe Gül; Hosgun, E. Zafer; Bozan, BerrinIn this study, mesoporous alumina was synthesized using aluminium isopropoxide as Al precursor and cationic surfactant cetyl trimethylammonium bromide (CTAB) as structure directing agent and it was tested in the dehydration reaction of fructose into 5-HMF. The experiments were carried out in a microwave reactor at 200 degrees C for 5 min. The various ratio of CTAB/Al2O3 and calcination temperature between 400 and 700 degrees C were selected as synthesis parameters. The synthesized samples were analyzed by BET and XRD. The highest surface area was obtained as 602.22 m(2)/g with the weight ratio of CTAB to Al2O3 of 1.00 at the calcination temperature of 400 degrees C. When calcination temperature increased from 400 to 700 degrees C, surface area decreased into 286.14 m(2)/g. N-2 adsorption/desorption isotherms of samples showed characteristic mesoporous type IV according to IUPAC classification. According to XRD patterns, all catalysts were in the amorphous structure. The maximum 5-HMF yield of 51% was achieved with the alumina catalyst calcined at 400 degrees C and CTAB/Al2O3 ratio of 1.0. Although the surface area decreased by rising the calcination temperature from 400 to 550 degrees C, the fructose conversion reached the highest value (97.54%).Öğe Synthesis, characterization and antibacterial activity of silver-doped TiO2 nanotubes(Pergamon-Elsevier Science Ltd, 2018) Aydin, M. Turkay Aytekin; Hoşgün, Halit Levent; Dede, Alper; Guven, KiymetOne-dimensional titanium dioxide (TiO2) nanotubes (TNTs) doped with silver (Ag) (% 5) were synthesized via two-step hydrothermal method. These nanotubes were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The impact of Ag-doped TiO2 nanotubes as antibacterial agents against three strains of Gram positive Staphylococcus aureus and a strain of Gram negative Escherichia coli was also investigated. XRD, FT-IR and Raman spectroscopy results showed that nanotubes were complete anatase phase. The potential biocidal effect of nanotubes to different S. aureus strains and E. coli was obtained. (C) 2018 Elsevier B.V. All rights reserved.Öğe Synthesis, characterization and photocatalytic activity of boron-doped titanium dioxide nanotubes(Elsevier Science Bv, 2019) Hoşgün, Halit Levent; Aydin, M. Turkay AytekinTwo-step hydrothermal method was used to prepare undoped and boron-doped one-dimensional titanium dioxide (TiO2) nanotubes. Structural properties, thermal stability and microstructural features of the fabricated undoped titanium dioxide nanotubes (TNTs) and boron-doped titanium dioxide nanotubes (BTNTs) were characterized by X-ray diffraction, Raman, Fourier transform infrared spectroscopy, nitrogen adsorption-desorption isotherms, scanning and transmission electron microscopy techniques. The photocatalytic activity of the fabricated nanotubes was evaluated by using methylene blue degradation. Boron addition to the titanium dioxide nanotubes up to 5% increased the photocatalytic methylene blue degradation efficiency. The achieved highest degradation efficiency was 81% and it was determined that higher (>5%) boron doped into the titanium dioxide nanotubes resulted in a decreased degradation efficiency. (C) 2018 Elsevier B.V. All rights reserved.Öğe The rheological, mechanical and aging properties of AEM/EPDM rubber blends(Springer Singapore Pte Ltd, 2021) Ozturk, Selda; Erbek Comez, Ezgi; Hoşgün, Halit LeventRubbers are used in many applications in industries such as chemistry, automotive, agriculture, and aviation. However, different types of rubbers should be used to meet the end-user expectations in all these areas of use. In recent years, the use of the blending method has obtained both superior properties and low-cost rubbers with the synergistic effect of two different rubbers. Ethylene acrylic rubber (AEM) is resistant to heat, chemicals, and ozone, but it is not well resistant to low aniline oil and polar solvents. In addition, AEMs are much more expensive than most standard elastomers. In this study, the upside-down method was applied to preparing the series of AEM and Ethylene propylene diene monomer (EPDM) rubber blends in a Banbury-type internal mixer. Rubber blends were a mixture of AEM and EPDM rubber in 90/10, 20/80, 30/70, and 60/40 phr rubber ratio variation. In addition, each of the blends was tested to determine rheological and mechanical properties such as tensile strength, elongation at break, hardness and compression set as well as thermal and oil (IRM 901 and IRM 903) aging effects. The 10% addition of EPDM rubber causes an increment in the compression set, the tensile strength, and elongation at break. It was observed that the tensile strength values of A100 and A90E10 samples were larger than 8 MPa and the hardness value did not change after aging in IRM 901 oil. A100 and A90E10 samples show satisfying results to the requirements SAEJ200M3EE708 standard.
