DSpace Arşivi :: by Yazar "Karaer, Hatice" değerine göre listeleniyor

Yazar "Karaer, Hatice" seçeneğine göre listele

Listeleniyor 1 - 12 / 12

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.
Adsorption of Methylene Blue from Aqueous Solution by Crosslinked Chitosan/Bentonite Composite
(TAYLOR & FRANCIS INC, 530 CHESTNUT STREET, STE 850, PHILADELPHIA, PA 19106 USA, 2015) Karaer, Hatice; Bulut, Yasemin
This article reports the application of a crosslinked chitosan/bentonite composite as adsorbent for the removal of a cationic dye, methylene blue (MB), from aqueous solution. Batch experiments were conducted to study the effects of contact time, initial concentration of adsorbate (50-200 mgL(-1)), temperature (298-313 K), agitation speed (90-150 rpm), and pH (2-10) on adsorption. The equilibrium experimental data were analyzed by the Freundlich and Langmuir models. The kinetic data obtained with different initial concentration and temperature were analyzed using a pseudo-first-order, pseudo-second-order, and intraparticle diffusion equations. Maximum adsorption capacity (Q(m)) was calculated at different temperatures (298, 308, and 313 K) as 95.24, 97.09, and 142.86 mg g(-1), respectively. The results showed that this novel adsorbent had a high adsorption capacity, making it suitable for use in the treatment MB-enriched wastewater.
Improvement of Synthesis and Dielectric Properties of Polyurethane/Mt-QASs+ (Novel Synthesis)
(Springer, 2016) Baysal, Gulay; Aydin, Haluk; Hosgoren, Halil; Uzan, Serhat; Karaer, Hatice
Polyurethane-based nanocomposites were prepared and their dielectric properties were characterized. Polyurethane (PU) composites were prepared with different organoclay content (1, 3, 5, and 10 wt% for all cases). The composites included quaternary ammonium salts such as 1-methyl-di-octyl-1 phenyl ammonium iodide (QAS-1), 1-methyl-di-nonyl-1 phenyl ammonium iodide (QAS-2), and 1-methyl-di-dodecyl-1 phenyl ammonium iodide (QAS-3) which were newly synthesized for modification of Na+-montmorillonite. Addition of aluminum silicate enhanced the dielectric properties at a constant concentration. Dielectric constants of nanocomposites compounded with 3 %- and 5 %-organoclay were close in value. The characterization of PU/organoclay composites was carried out using Fourier transform infrared and X-ray diffraction.
Modifiye edilmiş chitosan ile sulu çözelitden bazik boyarmaddelerin adsorpsiyonunun incelenmesi
(2017) Karaer, Hatice; Uzun, İlhan
Bu çalışmada chitosan öncelikle bazı halkalı anhidritler (ftalik anhidrit, maleik anhidrit ve trimellitik anhidrit) ile modifiye edildi. Chitosan, ftalik anhidrit ile modifiye edilen chitosan (FAC), maleik anhidrit ile modifiye edilen chitosan (MAC) ve trimellitik anhidrit ile modifiye edilen chitosan (TAC) sulu çözeltiden brillant yeşilini ve metilen mavisini adsorplama kapasitelerine göre karşılaştırıldı. TAC’ın diğer adsorplayıcılara göre bu boyarmaddeleri daha fazla adsorpladığı görüldü. Daha sonra TAC ile sulu çözeltiden brillant yeşilinin ve metilen mavisinin adsorpsiyonları sıcaklığa ve pH’a bağlı olarak incelendi. Her bir boyarmadde için farklı sıcaklıklarda elde edilen kinetik veriler Lagergren, Ho-McKay ve Weber Morris denklemlerine uygulandı ve pseudo ikinci-dereceden hız sabitleri (k2) ve gözenek difüzyon hız sabitleri (kp) belirlendi. Her iki boyarmaddeye ilişkin Lagergren çizimleri doğrusal olmadığından dolayı pseudo birincidereceden hız sabitleri (k1) ise belirlenemedi. TAC ile sulu çözeltiden brillant yeşili ve metilen mavisi adsorpsiyonuna ilişkin kinetik veriler Ho-McKay denklemine uyduğundan dolayı pseudo ikinci-dereceden hız sabitleri Arrhenius denklemine uygulandı ve bu boyarmaddelerin TAC üzerindeki adsorpsiyonuna ilişkin aktivasyon enerjileri (Ea) belirlendi. Ayrıca, TAC ile sulu çözeltiden brillant yeşiline ve metilen mavisine ilişkin farklı sıcaklıklardaki adsorpsiyon izotermleri belirlendi. TAC ile sulu çözeltiden brillant yeşilinin 298 K’deki adsorpsiyon izotermi Langmuir adsorpsiyon izotermine uyduğundan dolayı, bu sıcaklıktaki izoterm veriler Langmuir adsorpsiyon izoterminin çizgisel haline uygulandı ve Langmuir sabitleri (qm ve b) hesaplandı. TAC ile sulu çözeltiden metilen mavisinin adsorpsiyon izotermleri Freundlich adsorpsiyon izotermine uyduğundan dolayı, izoterm veriler Freundlich adsorpsiyon izoterminin çizgisel haline uygulandı ve Freundlich sabitleri (k ve n) hesaplandı.
Piridin ve pirimidin grupları içeren polifenollerin sentezi ve karakterizasyonu
(2016) Karaer, Hatice; Aydın, Haluk; Kaya, İsmet
Bu çalışmada üç farklı aldehit (2-hidroksibenzaldehit, 4-hidroksibenzaldehit ve 2- hidroksi-1-naftaldehit) monomerlerinden sulu bazik ortamda yükseltgeyici olarak NaOCl ve H2O2 oksidantları varlığında oksidatif polimerizasyon yöntemi kullanılarak üç farklı polialdehit (poli-2-hidroksibenzaldehit, poli-4-hidroksibenzaldehit ve poli-2-hidroksi-1- naftaldehit) bileşikleri sentezlendi. Sentezlenen polialdehit bileşiklerinin her birine pridin ve primidin grupları içeren altı farklı amin bileşikleri aşılanarak poli Schiff bazları sentezlendi. Sentezlenen bu polimerlerin yapıları FT-IR, 1 H-NMR, 13C-NMR, SEC ve SEM analizleri ile yapısal karakterizasyonu, optiksel özellikleri UV-vis ve floresans spektroskopisi yöntemleriyle, elektrokimyasal özellikleri CV analiziyle, katı hal iletkenlik ölçümleri dört nokta prob tekniğiyle, ısısal davranışları ise TG, DTA, DSC ölçümleriyle belirlendi. Sentezlenen polimerlerin elektriksel iletkenlikleri dörtlü prob tekniğiyle ölçüldü ve yarı iletken özellik gösterdikleri tespit edildi. SEC analizine göre sentezlenen polimerlerin sayıca ortalama molekül ağırlığı (Mn), ağırlıkça ortalama molekül ağırlığı (Mw) ve polidisperslik indeksi (PDI) değerleri bulundu. Mw, Mn ve PDI değerleri P-2HBA, P-2NAF ve P-4HBA polimerleri için sırasıyla; 46750, 35400 ve 1.32; 43400, 35600 ve 1.22; 24420 16805 ve 1.45 olarak bulundu. CV ile elektrokimyasal bant boşlukları (E’g), UV-Vis ölçümlerine göre ise optik bant boşlukları (Eg) hesaplandı. Polimerlerin Floresans analizleri DMF çözücü ortamında yapıldı ve piridin gruplarının pirimidin gruplarına göre floresans şiddetlerinin daha yüksek olduğu görüldü. Anahtar Kelimeler: Poli(imin), Poli(azometin), oksidatif polikondenzasyon
Removal of Methylene Blue from Aqueous Solution by Crosslinked Chitosan-g-Poly(Acrylic Acid)/Bentonite Composite
(Taylor & Francis Inc, 2015) Bulut, Yasemin; Karaer, Hatice
A new crosslinked chitosan-g-poly (acrylic acid)/bentonite composite (CS-g-PAA/BT) was prepared and used for the removal of methylene blue (MB). CS-g-PAA/BT was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The water absorbency for CS-g-PAA/BT was found to be 93 and 50 g H(2)Og(-1) in distilled water and 0.2% NaCl, respectively. The results showed that the adsorption of the MB on the CS-g-PAA/BT was effected by the initial dye concentration, the initial pH value, as well as the temperature. Both kinetics and thermodynamic parameters of the adsorption process were estimated. These data indicated an endothermic spontaneous adsorption process that kinetically followed the second-order adsorption process. Equilibrium experiments fitted well the Langmuir isotherm model, and the maximum monolayer adsorption capacity for the MB was 2000-2500 mg g(-1) at 298-313 K. The results of this study implied that CS-g-PAA/BT can be used a promising adsorbent for the removal of MB from wastewater.
Synthesis, characterization and electrochemical properties of poly (phenoxy-imine)s containing carbazole unit
(Springer Heidelberg, 2017) Kaya, Ismet; Copur, Sebra; Karaer, Hatice
Several new Schiff base polymers were synthesized via oxidative polymerization method in an aqueous alkaline medium in the presence of NaOCl as an oxidant and were confirmed by FT-IR, H-1-NMR, C-13-NMR and UV-Vis spectroscopic techniques. Furthermore, cyclic voltammetry measurements were carried out and the HOMO-LUMO energy levels and electrochemical band gaps (E-g') were calculated. Additionally, the optical band gaps (E-g) were determined using their UV-Vis spectra of the materials. The morphologic properties of the polymers were investigated by scanning electron microscopy. In addition, the number average molecular weight (M-n), weight average molecular weight (M-w) and polydispersity index values of the polymers were determined by gel permeation chromatography technique. Electrical conductivity measurements of the doped (with iodine) and undoped polymer related to doping time were carried out by four-point probe technique using a Keithley 2400 electrometer. Their thermal behaviors were determined by TG-DTA and DSC measurements. The synthesized compounds were soluble in common solvents such as DMF, THF and DMSO. Photoluminescence properties of the polymers were determined in different concentrations of DMF solvent.
Synthesis, characterization and electrochemical properties of poly(phenoxy-imine)s containing peril and tert-butyl units
(Elsevier B.V., 2019) Kaya, İsmet; Sandal, Bekir Süleyman; Karaer, Hatice
Schiff bases were obtained by condensation reactions of 2-aminophenol and 4-aminophenol with 4-isopropenylcyclohex-1-ene-1-carbaldehyde (peril aldehyde) and 3,5-di-tert-butyl-2-hydroxy benzaldehyde. Then, polymers of these compounds were prepared via oxidative polymerization method in THF in the presence of NaOCl as an oxidant. The structures of compounds were confirmed by some techniques such as FT-IR, 1H NMR, 13C NMR and UV–vis. Moreover, cyclic voltammetry (CV) was used to calculate the HOMO−LUMO energy levels and electrochemical band gaps (Eg′) of compounds. Electrochemical band gaps (Eg′) values of P1, P2, P3 and P4 polymers were found as 2.61, 2.65, 2.89 and 2.28 eV, respectively. Furthermore, TGA and DSC were employed to determine thermal properties of the Schiff bases and polymers. The photoluminescence (PL) properties of polymers were also determined in DMSO. Then, we found that their number-average molecular weight (Mn), weight average molecular weight (Mw) as well as polydispersity index (PDI) values by the size exclusion chromatography (SEC). Finally, we carried out their solubility tests in acetone, THF, chloroform, acetonitrile, methanol, ethyl acetate, n-hexane and DMSO.
Synthesis, characterization and using at the copper adsorption of chitosan/polyvinyl alcohol magnetic composite
(Elsevier, 2017) Karaer, Hatice; Kaya, Ismet
A chitosan/polyvinyl alcohol (CTN/PVA-Fe3O4) magnetic composite was prepared in one step and examined by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX), transmission electron microscopy (TEM), dynamic light scattering (DLS), Brunauer-Emmett-Teller (BET), thermal gravimetric analysis/differential thermal analysis (TGA-DTA) and differential scanning calorimetry (DSC). Effects of several parameters, such as temperature, pH, and initial concentration on removal of Cu(II) from aqueous solution by the CTN/PVA magnetic composite were studied as a function of contact time. Equilibrium data obtained from sorption of Cu(II) solutions having initial concentrations of 25 to 400 mg L-1 by sorption of the CTN/PVA magnetic composite at different temperatures (25, 35 and 45 degrees C) were applied to Langmuir and Freundlich adsorption isotherms. Maximum adsorption capacity (Q(max))was found to be 143 mg g(-1) by using Langmuir isotherm model, by which thermodynamic parameters (Delta H degrees, Delta G degrees and Delta S degrees) were also calculated. Activation energy was calculated by using rate constants for this model and its value was found 26.52 kJ mol(-1). (C) 2017 Elsevier B.V. All rights reserved.
Synthesis, characterization of magnetic chitosan/active charcoal composite and using at the adsorption of methylene blue and reactive blue4
(Elsevier Science Bv, 2016) Karaer, Hatice; Kaya, Ismet
In this study, a chitosan/activated charcoal (or carbon) (CTN/AC-Fe3O4) composite was obtained in one step, characterized several techniques such as by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, dynamic light scattering, Brunauer-EmmetTeller, thermogravimetric analysis/differential thermal analysis and differential scanning calorimetry techniques. The sorption the composite were investigated as kinetically and thermodynamically for removal of methylene blue (MB) and reactive blue4 (RB4) from aqueous solution. Effects of several parameters, such as initial temperature and initial concentration on removal of MB and RB4 from aqueous solution by the composite were investigated as a function of contact time. Maximum adsorption capacity (Qmax) was found to be 500 mg g(-1) at and 250 mg g(-1) at 318 K for MB, 298 K for RB4 respectively. Also, thermodynamic parameters such as Delta H-0, Delta G(0)and Delta S-0 were calculated by Langmuir adsorption isotherm model. Negative Gibbs free energy (Delta G(0)) implies that the adsorption is spontaneous and positive adsorption enthalpy (Delta H-0) demonstrates the process is endothermic for MB while negative adsorption enthalpy (Delta H-0) demonstrates the process is exothermic for RB4, respectively. (C) 2016 Elsevier Inc. All rights reserved.
Synthesis, characterization, and thermal decompositions of Schiff base polymers containing chitosan unit
(Springer, 2015) Karaer, Hatice; Kaya, Ismet
The most plentiful natural biopolymer chitin and chitosan have become center of attraction of all party because of an unusual combination of biological activities, mechanical and physical properties. The several chemical modifications such as oligomerization, alkylation, quternization, enzymatic modifications, and graft copolymerization along with many assorted modifications have been carried out. However, its applications have only been shown in acidic medium because of its poor solubility in neutral and basic pH. In view of rapidly growing interest in chitosan its chemical aspects and chemical modification studies are reviewed. Four different aldehyde types, namely 4-hydroxybenzaldehyde (4HBA), 2-hydroxybenzaldehyde (2HBA), vanillin (VAN), 3-thiophenecarboxaldehyde (3TPCA), and their poly(4-hydroxybenzaldehyde) (P4HBA), poly(2-hydroxybenzaldehyde) (P2HBA), and poly (vanillin) (PVAN) were treated with chitosan to obtain Schiff base polymers. Although some of the chitosan-based Schiff bases were present in the literature, contrary to the literature the aldehydes (4HBA, VAN, 2HBA) were polymerized via oxidative polycondensation, followed by their reaction with chitosan to provide the Schiff base polymers, which were characterized by several techniques such as FTIR, TGA-DTA, DSC, SEM-EDX, and UV-Vis. Also, the solid-state electrical conductivities values of the compounds were measured by four-point probe technique.
Synthesis, characterization, thermal and electrochemical properties of imine polymers containing pyridine and pyrimidine units
(Industrial Chemistry Research Inst, 2017) Karaer, Hatice; Kaya, Ismet; Aydin, Haluk
Schiff bases polymers were synthesized from 2-hydroxybenzaldehyde (2-HBA) vin oxidative polymerization method in an aqueous alkaline medium in the presence of NaOCI as an oxidant. Then, these polymeric Schiff bases were prepared from the polyaldehyde by grafting each of them with different amines containing pyridine and pyrimidine groups. The structures of polymers were confirmed by FT-IR, H-1 NMR, C-13 NMR, and UV-Vis measurements. The polymers were characterized by GPC and SEM analyses. Furthermore, their optical properties were determined by UV-Vis and fluorescence spectroscopy, their electrochemical properties by cyclic voltammetry (CV) analysis and solid state conductivity measurements by the four-point probe technique, their thermal behavior by TG, DTA, and DSC measurements. The electrical conductivity of the polymers was also measured and found that they are semiconductive. The number average molecular weight ((M) over bar (u)), the weight average molecular weight ((M) over bar (w)), and dispersity (D) values of the polymers were found from GPC analysis and were equal 5900, 5450 and 1.08, respectively, for poly(2-hydroxybenzaldehyde) (P-2HBA) polymer. Electrochemical energy gap (E-s) was found by CV, whereas optical band gap (E-s,) was determined by UV-Vis measurements.

Yazar "Karaer, Hatice" seçeneğine göre listele

Sayfa Başına Sonuç

Sıralama seçenekleri