Yazar "Uzun, Ilhan" seçeneğine göre listele

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    Adsorption of basic dyestuffs from aqueous solution by modified chitosan
    (Taylor & Francis Inc, 2013) Karaer, Hatice; Uzun, Ilhan
    The capability of chitosan to adsorb the basic dyestuffs is very low. For this purpose, chitosan was modified to increase its adsorption capability with some cyclic acid anhydrides in dimethyl sulfoxide. Then, chitosan and its derivatives, chitosan modified with maleic anhydride (CMA), chitosan modified with phthalic anhydride (CPA), and chitosan modified with trimellitic anhydride (CTA), were compared according to their capabilities to remove brilliant green (BG) and methylene blue (MB) from aqueous solution. It was determined that CTA adsorbed much more BG and MB. The 70.57% of BG (C-o: 50 ppm) and 71.86% of MB (C-o: 50 ppm) in the samples of 50 mL by 0.1 g CTA were adsorbed at room temperature and at a shaking rate of 140 rpm within 24 h. As a result of this, the adsorption of BG and MB by CTA was kinetically investigated as dependent on temperature and pH. Besides, the adsorption isotherms of each dyestuff by CTA were determined at different temperatures. Then, some kinetical and thermodynamical parametres were calculated by using experimental data.
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    Adsorption of some highly toxic dyestuffs from aqueous solution by chitin and its synthesized derivatives
    (Elsevier Science Bv, 2009) Akkaya, Guelbahar; Uzun, Ilhan; Guzel, Fuat
    The adsorption of indigo carmine (IC) and trypan blue (TB) by chitin was kinetically investigated as dependent on temperature and pH. Experimental data obtained at different temperatures for the adsorption of each dyestuff were applied to the pseudo first-order, the pseudo second-order and the intraparticle diffusion rate equations, and the pseudo first-order rate constants (k(1)), the pseudo second-order rate constants (k(2)) and the intraparticle diffusion rate constants (k(p)) at these temperatures were calculated, respectively. In addition, adsorption isotherms of each dyestuff by chitin were also determined at different temperatures. It was seen that adsorption isotherms fitted the H type. Chitin was then modified via ring-opening reaction with cyclic acid anhydrides (succinic, maleic and 1,2,4-benzenetricarboxylic) in lithium chloride/N,N-dimethylacetamide. Chitin derivatives obtained were compared according to their capabilities to adsorb IC and TB. It was determined that IC and TB were more adsorbed by chitin modified with 1,2,4-benzenetricarboxylic anhydride (CBA) and chitin modified with maleic anhydride (CMA), respectively. 31.33% of IC (C-0: 300 ppm) by CBA, and 44.29% of TB (C-0: 200 ppm) by CMA were adsorbed. Then, the adsorption of IC by CBA and of TB by CMA was kinetically investigated as dependent on temperature. The constants k(1), k(2) and k(p) related to the adsorption of IC by CBA and of TB by CMA were calculated as stated above. (C) 2009 Elsevier B.V. All rights reserved.
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    The calculation of electronic properties of an Ag/chitosan/n-Si Schottky barrier diode
    (Elsevier Science Sa, 2007) Akkilic, Kemal; Uzun, Ilhan; Kilicoglu, Tahsin
    In this study, the film of chitosan by adding the solution of chitosan being a polymeric compound on the top of an n-Si substrate and then by evaporating solvent was formed. It was seen that the chitosan/n-Si contact demonstrated clearly rectifying behavior and the reverse curves exhibit a weak bias voltage dependence by the current-voltage (I-V) curves studied at room temperature. Average barrier height and ideality factor values for this structure were determined as 0.94 eV and 1.81, respectively. Furthermore, the energy distribution of the interface state density located in the semiconductor band gap at the chitosan/n-Si substrate in the energy range (E-c-0.785) to (E-c-0.522) eV have been determined from the I-V characteristics. The interface state density N-ss ranges from 5.39 x 10(12) cm(-2) eV(-1) in (E-c-0.785) eV to 1.52 x 10(13) cm(-2) eV(-1) in (E-c-0.522) ev. The interface state density has an exponential rise with bias from the midgap towards the bottom of the conduction band. (c) 2007 Elsevier B.V. All rights reserved.
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    Characterization of synthesized new chitin derivatives and Schottky diodes made using these derivatives
    (Springer, 2020) Uzun, Ilhan; Orak, Ikram; Karakaplan, Mehmet; Yagmur, Hatice Karaer; Yalcin, Serife Pinar; Akkilic, Kemal
    In this study, two new chitin derivatives were firstly synthesized. The products formed as a result of the reactions between chitin with 4-bromo-1,8-naphthalic anhydride and 4,4 '-oxydiphthalic anhydride were abbreviated as C4B18NA and C44 ' OA, respectively. The structures of the chitin derivatives were illuminated by various spectroscopic methods (FTIR, NMR, and XRD), and it was thus confirmed that they were synthesized. The surface structures of the chitin derivatives were investigated by SEM technique. Then, two separate diodes were made using aluminum as metal, the chitin derivatives as interfacial layer, and p-Si as semiconductor. Some important properties of the diodes made were determined both in the dark and under an illumination of 100 mW/cm(2). It was seen that the diodes are more ideal than most of the diodes where aluminum and p-type silicon were used as metal and semiconductor in their structures, respectively.
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    Determination of Electrical and Photoelectrical Properties of Schottky Diodes Made Using New Chitin Derivatives Synthesized as Interface Layer
    (Springer, 2021) Uzun, Ilhan; Orak, Ikram; Yagmur, Hatice Karaer; Karakaplan, Mehmet; Yalman, Murat
    5-(2,4-dichlorophenyl)-2-furoic acid and anthraquinone-2-carboxylic acid were reacted separately with chitin. The synthesized products were characterized by various spectroscopic methods (FTIR, NMR and XRD) and were abbreviated as C524D2FA and CA2CA, respectively. The surface of the chitin derivatives, pulverized by pounding in mortar, was examined by SEM technique. Then, two different diodes were made by using these chitin derivatives as an interface layer. Al as metal and p-Si as semiconductor were used in the construction of the diodes. Some important properties of these diodes made were determined both in the dark and under an illumination of 100 mW/cm(2). The Al/CA2CA/p-Si diode has been found to be more ideal than the Al/C524D2FA/p-Si diode conducted in this study and many other diodes made using Al and p-Si in other studies up to now.
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    Evaluation of synthesized new chitin derivatives in Schottky diode constructions
    (Taylor & Francis Inc, 2020) Uzun, Ilhan; Aksoy, Onder; Topal, Giray; Celik, Omer; Ocak, Yusuf Selim
    Chitin was reacted with coumarin-3-carboxylic acid (C3CA) and benzophenone-3,3MODIFIER LETTER PRIME,4,4MODIFIER LETTER PRIME-tetracarboxylic dianhydride (B33MODIFIER LETTER PRIME44MODIFIER LETTER PRIMETD), and the synthesized chitin derivatives (CC3CA and CB33MODIFIER LETTER PRIME44MODIFIER LETTER PRIMETD) were characterized by spectroscopic methods and other techniques (FTIR, C-13 CP/MAS solid-state NMR, XRPD, SEM, and TGA). Also, the charge carrier density, hole mobility, and electrical conductivity of CB33MODIFIER LETTER PRIME44MODIFIER LETTER PRIMETD were determined. Lastly, Schottky diodes were constructed using these derivatives, and some electrical properties (barrier height, ideality factor, and series resistance) and photoelectrical properties (light sensitivity, short circuit current, and open circuit voltage) of the diodes were determined. It was seen that the diodes have very good ideality factor and light sensitivity.
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    Kinetics and thermodynamics of the adsorption of some dyestuffs from aqueous solution by poplar sawdust
    (Elsevier Sci Ltd, 2008) Pekkuz, Hueseyin; Uzun, Ilhan; Guzel, Fuat
    The effect of temperature on the adsorption of metanil yellow (MY) (acidic) and methylene blue (MB) (basic) by poplar sawdust was investigated. In addition, the amounts of NaHCO3, NaCO3, NaOH and C2H5ONa adsorbed by I g of poplar sawdust to determine its surface acidity were also determined. Kinetical data obtained at different temperatures (293 K, 313 K and 333 K) for the adsorption of each dyestuff by poplar sawdust were applied to the pseudo first-order, the pseudo second-order and the intraparticle diffusion equations, and the rate constants of first-order adsorption (k1), the rate constants of second-order adsorption (k2) and intraparticle diffusion rate constants (k(p)) at these temperatures were calculated, respectively. In addition, isothermal data obtained at different temperatures (293 K, 313 K and 333 K) for the adsorption of each dyestuff by poplar sawdust were applied to thermodynamical equations, and thermodynamical parameters (Delta G, Delta H and Delta S) were also calculated. (c) 2007 Elsevier Ltd. All rights reserved.
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    Kinetics of the adsorption of reactive dyes by chitin
    (Elsevier Sci Ltd, 2007) Akkaya, Gulbahar; Uzun, Ilhan; Guzel, Fuat
    The effect of initial concentration, temperature, shaking rate and pH on the adsorption of reactive yellow 2 (RY2) and reactive black 5 (RB5) by chitin (Sigma C 9213) was investigated. Experimental data obtained at different temperatures for the adsorption of each dyestuff by chitin were applied to pseudo first-order, pseudo second-order and Weber-Morris equations, and the rate constants of first-order adsorption (k(1)), the rate constants of second-order adsorption (k(2)) and pore diffusion-rate constants (k(p)) at these temperatures were calculated, respectively. In addition, the adsorption isotherms of each dyestuff by chitin were also determined at different temperatures. (c) 2005 Elsevier Ltd. All rights reserved.
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    New chitin derivatives and their Schottky diodes: Synthesis and characterization
    (Sage Publications Ltd, 2019) Aksoy, Onder; Uzun, Ilhan; Topal, Giray; Celik, Omer; Ocak, Yusuf Selim; Batibay, Derya
    First, chitin was reacted with 4,5-dichlorophthalic acid and diphenic acid, and thus two new chitin derivatives (C45DA and CDA) were synthesized. Then, C45DA and CDA were characterized by various spectroscopies and techniques (FTIR, C-13 CP-MAS solid-state NMR, XRPD, SEM, and TGA/DTA). Besides, some electrical properties of C45DA were measured. After the characterization process, the Schottky diodes of C45DA and CDA were made. It was determined that these diodes showed photodiode characteristics at the same time. Later on, both electrical properties (phi(b), n, and R-s) and photoelectrical properties (I-illumination/I-Dark, I-SC and V-OC) of these diodes were determined.
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    Schottky Diodes Based on the New Chitin Derivatives
    (Maik Nauka/Interperiodica/Springer, 2019) Aksoy, Onder; Uzun, Ilhan; Topal, Giray; Ocak, Yusuf Selim; Celik, Omer; Batibay, Derya
    New chitin derivatives were synthesized by the reactions of chitin with o-acetylsalicyloyl chloride and phthaloyl chloride and their structure was characterized by FTIR and C-13 CP-MAS solid-state NMR spectroscopy and X-ray powder diffraction technique. Also, the thermal and surface properties of the chitin derivatives were investigated by thermogravimetric analysis and a scanning electron microscope. In addition, some electrical properties of the polymers were determined using Hall effect technique. Then, the Schottky diodes were fabricated by the formation of interlayers of chitin derivatives between Au metal and n-Si semiconductor, and the electrical and photoelectrical properties of the diodes were determined.
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    Synthesis, characterization, and Schottky diode applications of low-cost new chitin derivatives
    (Springer, 2018) Aksoy, Onder; Uzun, Ilhan; Topal, Giray; Ocak, Yusuf Selim; Celik, Omer; Batibay, Derya
    In this study, low-cost two new chitin derivatives were first synthesized. Products formed in the consequence of the reaction of chitin with 4-nitrobenzoyl chloride and 3,5-dinitrobenzoyl chloride were named C4NC and C35DC, respectively. Then, C4NC and C35DC were characterized by FTIR and C-13 CP-MAS solid-state NMR spectroscopies and X-ray powder diffraction technique. Surface topography and composition of C4NC and C35DC with a scanning electron microscope were investigated. Mass loss in C4NC and C35DC with thermogravimetric analysis method was determined as a function of increasing temperature. Endothermic and exothermic transitions in C4NC and C35DC were investigated with differential thermal analysis and differential scanning calorimetry techniques. Later on, charge carrier density, hole mobility, and electrical conductivity values of C4NC and C35DC were determined. Besides, Schottky diodes of C4NC and C35DC were constructed, and several parameters related to these diodes were determined. Finally, the sensitivity of these diodes to light was studied.