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Öğe Adsorption of some heavy metal ions from aqueous solution by activated carbon and comparison of percent adsorption results of activated carbon with those of some other adsorbents(2000) Güzel, Fuat; Uzun, İlhanIn this study, removal of some heavy metals ions $(Mn^{2+}, Fe^{2+}, Ni^{2+} and Cu^{2+})$ from aqueous solution by adsorption was investigated. For this purpose, high-grade MnSO4.H2O, FeSO4.7H2O, NiSO4.7H2O and CuSO4.5H2O were used as heavy metal samples. The commercial activated carbon (Merck 2514), chitosan and agar were used as adsorbents. The pH of each solution was not controlled. This is because the net interaction between the adsorbent and the heavy metal could be disturbed by the buffer solution. Therefore, all experiments were carried out in a pH range from 5.3 to 5.5. The equilibrium adsorption contact times were determined for M - 2514. The adsorption rate constants were determined from obtained kinetics curves suitable for first degree of rate kinetics. Adsorption isotherms of heavy metals on M - 2514 from aqueous solution were determined. These adsorption isotherms were seen to be consistent with Freundlich's adsorption isotherm. k and n constants were determined from Freundlich's linear equation. In addition, M - 2514, chitosan and agar were compared according to their percent uptake yields of the heavy metals.Öğe Aktif karbonla sulu çözeltiden bazı ağır metallerin adsorpsiyon kinetiği ile izotermlerinin incelenmesi ve diğer bazı adsorplayıcılarla yüzde adsorpsiyon sonuçlarının karşılaştırılması(2018) Uzun, İlhan; Güzel, FuatBu çalışmada, sulu çözeltiden bazı ağır metallerin (MnS04.H20, FeS04.7H20, NİSO4.7H2O ve CuS04.5H20) çeşitli adsorplayıcılarla uzaklaştırılması incelendi. M- 2514, chitosan ve agar adsorplayıcılar olarak kullanıldı. M-2514 ile ağır metallerin denge temas süreleri sırasıyla 4 gün, 2 gün, 2 gün ve 1.5 gün ve adsorpsiyon hız sabitleri sırasıyla 0.0017 s"1, 0.0209 s"1, 0.0308 s"1 ve 0.0395 s"1 olarak bulundu. Bu ağır metallerin adsorpsiyon izotermlerinin Freundlich adsorpsiyon izotermine uydukları görüldü. Freundlich den Meminin k sabitleri sırasıyla 0.0574, 0.9052, 0.5256 ve 2.3940 ve n sabitleri sırasıyla 1.3393, 1.3934, 2.2573 ve 2.5786 olarak bulundu. Ayrıca, M-2514, chitosan ve agar ağır metallerin yüzde uzaklaştırılma verimlerine göre karşılaştırıldı. 24 saat ve 200 ppm sırasıyla her bir ağır metal iyonunun temas süresi ve başlangıç konsantrasyonu olarak seçildi. Bu karşılaştırmada aşağıdaki sıra elde edildi; mangan için agar > aktif karbon > chitosan, demir için chitosan > aktif karbon > agar, nikel için chitosan > aktif karbon > agar ve bakır için chitosan > aktif karbon > agar.Öğe Determination of the micropore structures of activated carbons by adsorption of various dyestuffs from aqueous solution(2002) Güzel, Fuat; Uzun, İlhanIn this study, some activated carbons prepared from sour cherry pits under various conditions were investigated. For comparison purposes, the commercial activated carbons Merck-2514 and Merck-2184 were used. The nitrogen adsorption isotherms at 77 K were used as reference for comparison, while p-nitrophenol, methylene blue, orange-II and victoria blue adsorptions were determined from aqueous solution at 298 K. It was clear from the specific surface area values obtained that the best activated carbon was obtained by activation for 4 hours following the chemical activation. Its adsorption properties are closer to the levels of the Merck commercial carbons. It was concluded that the characterization of microporous structure, and the testing of the removal of organic impurities from aqueous solution for active carbons having high adsorption ability from the gas phase, can generally be carried out by adsorption of organic solutes whose molecular sizes are smaller than the micropore size (1.5 nm) of the adsorbent.Öğe Evaluation of synthesized new cellulose derivatives to make diodes and investigation of electrical and photoelectrical characteristics of these diodes(Elsevier Ltd., 2024) Uzun, İlhan; Taşyürek, Lütfi Bilal; Orak, İkram; Karakaplan, MehmetFirstly, two new cellulose derivatives (CelB33′44′TD and Cel44′OA) were synthesized, which were confirmed by FTIR and 13C CP-MAS NMR spectra. These derivatives were then used in the construction of new diodes (Au/CelB33′44′TD/p-Si and Au/Cel44′OA/p-Si). Later, the atomic force microscope (AFM) images of the interface layers were taken, and the current–voltage (I–V) graphs of the diodes were determined both in the dark and under different illumination intensities (DIIs). Using the Bethe's thermionic emission (TE) theory the ideality factors and barrier heights of the diodes, using the Cheung & Cheung functions the ideality factors, series resistances and barrier heights of the diodes, and using the Norde function the barrier heights and series resistances of the diodes were calculated. Finally, the capacitance–voltage (C–V) and conductance–voltage (G–V) graphs of the diodes at different frequencies (DFs) were examined and some frequency-dependent electrical parameters of the diodes were calculated using the 1/C2–V plots.Öğe External mass transfer studies during the adsorptions of some dyestuffs and p- nitrophenol onto chitosan from aqueous solution(2004) Uzun, İlhan; Güzel, FuatThe effect of temperature on the adsorptions of some dyestuffs [orange II (O-II), crystal violet (CV) and reactive blue 5 (RB5)] and an ideal adsorbate p-nitrophenol (PNP) by chitosan (Sigma C 3646) from aqueous solution was investigated. The experimental data related to adsorption isotherms were applied to linear forms of the equations that they fitted, and isotherm constants were calculated. Since the isotherm curves obtained for the adsorptions of O-II and CV by chitosan fitted the Langmuir adsorption isotherm, the Langmuir constants ($q_m$ and b) related to the adsorption isotherms of these dyestuffs together with their kinetical data at different temperatures were applied to the equation of McKay et al., and external mass transfer coefficients $(k_f)_1$ at these temperatures were calculated. In addition, kinetic data obtained for each dyestuff and PNP at different temperatures were applied to a further equation developed by Weber-Mathews, and $(k_f)_2$ constants at these temperatures were calculated.Öğe Methods of determining the degree of crystallinity of polymers with X-ray diffraction: a review(Springer Science and Business Media B.V., 2023) Uzun, İlhanIn this study, the methods developed to determine the degree of crystallinity of polymers by X-ray diffraction (XRD) until the date which this study was done were investigated in chronological order. With this study, the concept of degree of crystallinity has been proposed instead of many concepts used to express the crystallinity of polymers. All figures related to the methods had been redrawn. By using the same symbol for the same concept, the formulas used in the methods have been updated and the methods have been made more understandable for application in new studies. Besides, the crystallinity values obtained in the studies in which the methods were developed were given in tables. Finally, the applications in other studies of the methods were investigated.Öğe Physicochemical characterization and the comparison of chitin and chitin modified with maleic anhydride(Oriental Scientific Publishing Company, 2015) Uzun, İlhan; Çelik, ÖmerFirstly, chitin was modified via ring-opening reaction with maleic anhydride in lithium chloride/ N,N-dimethylacetamide. Then, both chitin and chitin modified with maleic anhydride (CMA) were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) method, ultraviolet-visible (UV-Vis) spectroscopy, and scanning electron microscopy (SEM). Thermogravimetric analysis (TGA) was performed to investigate the thermal stability of chitin and CMA. TGA results showed that chitin is thermally more stable than CMA. In addition, the electrical conductivity of chitin and CMA was also measured. Electrical conductivity measurement results showed that the electrical conductivity of CMA (4.3x10-4 S cm-1) is more than that of chitin (6.5 x 10-6 S cm-1).Öğe Sulu çözeltiden chitosan ve mcm-chitosan ile bazı boyarmaddelerin adsorpsiyonunun kinetik ve termodinamik olarak incelenmesi(Dicle Üniversitesi, Fen Bilimleri Enstitüsü, 2001) Uzun, İlhan; Güzel, FuatBu çalışmada, sulu çözeltiden chitosan ile bazı boyarmaddelerin (oranj II, kristal viyole, reaktif mavisi 5) ve ideal adsorplanan olarak kabul edilen p-nitro fenolün adsorpsiyonlan başlangıç derişimine, sıcaklığa ve çalkalama hızına bağlı olarak incelenmiştir. Her bir boyarmadde ve p-nitro fenol için farklı sıcaklıklarda elde edilen kinetik veriler değişik kinetik denklemlerde (Lagergren denklemi, Weber-Morris denklemi, McKay et al. denklemi) değerlendirilerek değişik kinetik parametreler hesaplanmıştır. Ayrıca her bir boyarmadde ve p-nitro fenol için farklı sıcaklıklarda izoterm çalışması yapılarak izoterm eğriler elde edilmiştir. Bu izoterm eğriler uydukları izoterm denklemlerin çizgisel ifadelerinde değerlendirilerek izoterm sabitleri ve adsorpsiyon izotermleri Langmuir adsorpsiyon izotermine uyan boyarmaddeler için, Langmuir b sabiti termodinamik bağıntılarda değerlendirilerek termodinamik parametreler hesaplanmıştır. Daha sonra chitosan modifiye edilerek yüzey özelliği değiştirilmiştir. Sulu çözeltiden bu modifiye edilmiş chitosan ile (MCM-chitosan) oranj II ve kristal viyole adsorpsiyonlan sıcaklığa bağlı olarak incelenmiştir. Her iki boyarmadde için farklı sıcaklıklarda elde edilen kinetik veriler yukarda belirtilen kinetik denklemlerde değerlendirilerek kinetik parametreler hesaplanmıştır. Ayrıca her iki boyarmadde için farklı sıcaklıklarda izoterm çalışması yapılarak izoterm eğriler elde edilmiştir. Kristal viyole için elde edilen izoterm eğriler Langmuir izotermine uyduğundan dolayı bu izoterm eğriler Langmuir çizgisel denkleminde değerlendirilerek Langmuir sabitleri ve Langmuir b sabitleri termodinamik bağıntılarda değerlendirilerek kristal viyole adsorpsiyonu için termodinamik parametreler hesaplanmıştır.Öğe Synthesis and characterization of new cellulose derivatives and evaluation of cellulose and these new cellulose derivatives in diode construction(Springer, 2023) Uzun, İlhan; Yiğit, Evin; Karakaplan, Mehmet; Orak, İkramFirst, two new cellulose derivatives (Cel35DC and CelPC) were synthesized, and the synthesized cellulose derivatives were characterized by FTIR and 13C CP-MAS NMR spectra. Next, three different diodes (Al/cellulose/p-Si, Al/Cel35DC/p-Si, and Al/CelPC/p-Si) were made. After, the AFM images of spin-coated thin films were taken. Then, the current–voltage curves of these diodes were determined both in the dark, in room light and under different illumination intensities. In addition, the current–voltage relationships of the diodes were examined in light on and off conditions to determine whether the diodes made have good photostability. Lastly, the rectification ratios, ideality factors, reverse saturation currents, barrier heights, series resistances and shunt resistances of the diodes made using the necessary methods and formulas were calculated.Öğe Synthesis and physicochemical characterization of chitin derivatives(2013) Uzun, İlhan; Topal, GirayFirstly, chitin derivatives were synthesized. For this purpose, chitin was modified via ring-opening reaction with cyclic anhydrides in lithium chloride/N,N-dimethylacetamide. Then, chitin derivatives synthesized were characterized by FTIR, 1H NMR, 13C NMR, and U-Vis spectroscopies and scanning electron microscopy. Thermogravimetric analysis was performed to investigate the thermal stability of chitin derivatives. Thermogravimetric analysis results showed that chitin modified with trimellitic anhydride is thermally more stable than chitin modified with phthalic anhydride. In addition, the electrical conductivity of chitin modified with phthalic anhydride and trimellitic anhydride was also measured. Electrical conductivity measurement results showed that the electrical conductivity of chitin modified with trimellitic anhydride (1.2 × 10 - 4 S cm -1) is higher than that of chitin modified with phthalic anhydride (9.2 × 10 - 5 S cm -1).Öğe Synthesis of canthaxanthin from beta-carotene and evaluation of both substances in diode construction(Springer, 2022) Uzun, İlhan; Orak, İkram; Sevgili, Ömer; Yiğit, Evin; Karakaplan, MehmetFirst, canthaxanthin was synthesized from beta-carotene, and it was confirmed by its FTIR spectrum that the synthesized substance was canthaxanthin. Then, three different diodes (Al/beta-carotene/n-Si, Al/canthaxanthin/n-Si, and Al/canthaxanthin/p-Si) were made using these substances for interface layer. The current-voltage curves of the diodes were determined both in the dark and under an illumination of 100 mW/cm(2) at 300 K. The ideality factors, barrier heights, and series resistances of the diodes in the dark and 300 K were calculated according to Bethe's thermionic emission (TE) theory, Norde function, and Cheung and Cheung method. Then, the effect of temperature on the current-voltage curves of the diodes was investigated. The ideality factors and barrier heights of the diodes at these temperatures were calculated only according to the TE theory. Finally, the effect of frequency on the capacitance-voltage and conductance-voltage curves of the diodes was investigated
