Person: KAHRAMAN, MEMET VEZİR
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KAHRAMAN
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MEMET VEZİR
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Publication Metadata only Sulfathiazole-based novel UV-cured hydrogel sorbents for mercury removal from aqueous solutions(PERGAMON-ELSEVIER SCIENCE LTD, 2009) KÖK YETİMOĞLU, ECE; Yetimoglu, Ece Koek; Kahraman, Memet Vezir; Bayramoglu, Guelay; Ercan, Oezgen; Apohan, Nilhan KayamanSulfathiazole-based novel hydrogel sorbents P(Sulti/hydroxyethyl methacrylate (HEMA)/acrylic acid (AAc)) were prepared by UV irradiation and used for the removal of mercury(II) ion from aqueous media. Hydrogels have been characterized by SEM and thermogravimetric analysis (TGA) techniques. The influence of the uptake conditions was investigated; maximum Hg(II) ion adsorption capacity obtained was 13.46 +/- 1.15mg g(-1) at pH 5.0. The hydrogels were tested several times without loss of adsorption capacity. The selectivity of the hydrogel towards to Hg(II), Cd(II) and Zn(II) ions tested was Hg>Cd>Zn. (C) 2008 Elsevier Ltd. All rights reserved.Publication Metadata only Preparation and characterization of UV-curable polymeric support for covalent immobilization of xylanase enzyme(ELSEVIER, 2011) KAHRAMAN, MEMET VEZİR; Akdemir, Zumrut Seden; Demir, Serap; Kahraman, M. Vezir; Apohan, Nilhan KayamanThe hydroxyl group of poly(ethylene glycol) monoacrylate (PEGMA) was activated by 1 1'-carbonyldiimidazole (CDI) and then a xylanase enzyme was immobilized to amine active PEGMA UV-curable polymeric support formulation was prepared by mixing the xylanase bonded PEGMA aliphatic polyester 2-hydroxyethyl methacrylate (HEMA) poly(ethylene glycol) diacrylate (PEGDA) and photoinitiator After UV irradiation the enzymatic activity of the polymeric matrix was evaluated and compared with the corresponding free enzyme By immobilization the temperature resistance of the enzyme was improved and showed maximum activity at 60 C pH dependent activities of the free and immobilized enzymes were also investigated and it was found that the pH of maximum activity for the free enzyme was 60 while for the optimal pH of the immobilized enzyme was 65 The immobilized enzyme retained 75% of its activity after 33 runs The morphology of the polymeric support was characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) coupled with SEM was used to explore the chemical composition The results have confirmed the evidence of enzyme in the structure of the polymeric material (c) 2010 Elsevier B V All rights reservedPublication Metadata only UV curable sulfonated hybrid materials and their performance as proton exchange membranes(ELSEVIER, 2009) KAHRAMAN, MEMET VEZİR; Gurtekin, M.; Kayaman-Apohan, N.; Kahraman, M. V.; Menceloglu, Y.; Gungor, A.In this study 2-acrylamido-2-methylpropanesulfonic acid (AMPS) containing UV curable nanocomposite membranes were prepared by using the sol-gel method. Tetraethylorthosilicate (TEOS), and 3-(methacryloyloxy)propyl trimethoxysilane (MAPTMS) were used, respectively as an inorganic precursor and coupling agent. Cross linking agents such as poly(ethylene glycol diacrylate) (PEGMA) and ethylene glycol dimethacrylate (EGDMA) were used to arrange the mechanical and physical properties of the resulting hybrid membrane. The hybrid formulation polymerized under UV irradiation and the gel percentage, water uptake of the membranes were calculated. The polymerization conversion of the organic part was investigated by using photo-differential scanning calorimetry (photo-DSC). The thermal and mechanical properties of the membranes indicated good stability. The morphological structure of membranes was investigated by scanning electron microscopy (SEM). In addition proton conductivity and methanol selectivity measurements were performed. The proton conductivity of the AMPS20-SOLGEL30 nanocomposite membrane is about 0.138 S cm(-1) at 50 degrees C. Selectivity toward methanol for the same membrane is very low with a selectivity factor of alpha = 0.032, which satisfies the requirements for DMFC applications. (C) 2009 Elsevier Ltd. All rights reserved.Publication Metadata only Development of photopolymerized fluorescence sensor for glucose analysis(ELSEVIER SCIENCE SA, 2013) KÖK YETİMOĞLU, ECE; Cubuk, Soner; Yetimoglu, Ece Kok; Kahraman, M. Vezir; Demirbilek, Pinar; Firlak, MelikeThe sensing membrane was prepared by photopolymerization of 4-vinylphenylboronicacid (VPBA), hydroxyethylmethacrylate (HEMA) and poly(ethylene glycol) diacrylate (PEG-DA). The membran is capable of determining glucose between 2.78 x 10(-4) mM and 5.56 x 10(-3) mM with a limit of detection of 0.89 x 10(-5) mM, and limit of quantification 3.17 x 10(-3) mM (n = 7). It can be completely regenerated by using distilled water. The sensor performance characteristics such as response time, dynamic working range and sensitivity were reported. The proposed sensor was then applied successfully for the determination of glucose in blood samples. The optical sensor was stable, cost effective, easy to prepare, rapid and simple for the determination of glucose. (C) 2013 Elsevier B.V. All rights reserved.Publication Metadata only Preparation of fluorine containing hybrid coatings: investigation of coating performance onto ABS and PMMA substrates(WILEY, 2011) KARTAL, İLYAS; Kahraman, Memet Vezir; Akdemir, Zumrut Seden; Kartal, Ilyas; Kayaman-Apohan, Nilhan; Gungor, AtillaUV-curable fluorinated organic-inorganic hybrid coatings were prepared by the sol-gel technique. Perfluorinated urethane modified alkoxysilane was synthesized by the reaction between perfluoro alcohol and 3-isocyanatopropyltrimethoxysilane. The prepared formulations were applied onto poly(methyl methacrylate) (PMMA) and acrylonitrile butadiene styrene (ABS) panels and polymerized by UV-curing. The properties of the hybrid coatings such as hardness, chemical resistance, thermal stability, surface morphology, double bond conversion, and also contact angle measurements were investigated. Contact angle measurements have shown that the addition of fluorinated silane precursor to the hybrid system improved the water repellency and increased the contact angle from 65 degrees to 106 degrees. Copyright (C) 2009 John Wiley & Sons, Ltd.Publication Metadata only Removal of Pb2+ and Cd2+ ions from aqueous solutions using guanidine modified hydrogels(WILEY-BLACKWELL, 2011) KÖK YETİMOĞLU, ECE; Yetimoglu, Ece Kok; Firlak, Melike; Kahraman, Memet Vezir; Deniz, SabahattinIn this study, experimental measurements have been made on the batch adsorption of cadmium and lead ions from aqueous solutions using poly(guanidine modified 2-acrylamido-2-methylpropan sulfonic acid/acrylic acid/N-vinylpyrrolidone/2-Hydroxyethyl methacrylate), P(AMPSG/AAc/NVP/HEMA) hydrogels. The guanidyl end group bearing AMPSG monomer was synthesized from the reaction of AMPS and guanidine. The hydrogels were prepared by UV-curing technique. The morphology of the dry H10-hydrogel sample was examined by SEM. The influence of the uptake conditions, such as pH, functional monomer per cent, contact time, initial feed concentration, and foreign metal ions on the metal ion binding capacity of hydrogel, was also tested. The selectivity of the hydrogel toward the different metal ions tested was Hg(II) > Pb(II) > Au(III) > Cd(II). The adsorption isotherm models were applied to the experimental data, and it was seen that the Langmuir isotherm model was the best fit for the adsorption of Cd(II) and Pb(II) ions on P(AMPSG/AAc/NVP/HEMA) hydrogel. It was found that adsorbed lead and cadmium ions on P(AMPSG/AAc/NVP/HEMA) hydrogel can be effectively desorbed by acid leaching and the regenerated P(AMPSG/AAc/NVP/HEMA) hydrogel can be reused almost five times less without any loss of adsorption capacity. Copyright (C) 2009 John Wiley & Sons, Ltd.Publication Metadata only Flame retardance of epoxy acrylate resin modified with phosphorus containing compounds(ELSEVIER SCIENCE SA, 2004) KAHRAMAN, MEMET VEZİR; Kahraman, MV; Kayaman-Apohan, N; Arsu, N; Gungor, AIn this work, UV radiation curing of allyldiphenyl phosphine oxide (ADPPO) and 4,4'-bis(allyloxyphenyl) phenyl phosphine oxide (DAPPO) monomers with epoxy acrylate resin in the presence of a photoinitiator was studied and their flame-retardant performance compared with pure epoxy acrylate film. The structures of allyl functional phosphorus compounds were characterized by FT-IR, H-1 NMR, C-13 NMR and all spectra were consistent with the expected structures. The polymerization behavior of both allyl functional monomers was followed in detail by monitoring the disappearance of acrylate and allyl groups by real-time infrared spectroscopy. It was obtained that the reactivity of DAPPO monomer is higher than ADPPO. In the case of ADPPO, chain transfer to monomer basically predominates. In each monomer, a tack free coating was obtained immediately upon irradiation. The addition of DAPPO leads to an improvement of the thermal and flame-retardant properties of the polymeric films. Thermal gravimetric analysis of DAPPO containing polymeric films gave higher char yield compared with UV cured pure epoxy acrylate resin. (C) 2004 Elsevier B.V. All rights reserved.Publication Metadata only UV Cured Polymeric Optical Fluorescence Sensor for the Determination of Au (III)(WILEY-V C H VERLAG GMBH, 2014) KÖK YETİMOĞLU, ECE; Cubuk, Soner; Yetimoglu, Ece Kok; Kahraman, M. Vezir; Kenan, SibelThe recognition and sensing of the biologically and environmentally important metal ions has emerged as a significant goal in the field of chemical sensors in recent years. Among the various analytical methods, fluorescence has been a powerful tool due to its simplicity, high detection limit and application to bio imaging. In this study, UV cured polymeric optical sensor for Au (III) ion based on a fluorescence membrane has been developed. The response characteristics of the sensor including dynamic range, pH effect and response time were systematically investigated. The influences of the conditions such as pH, response time on the metal ion binding capacity of membrane were also tested.Publication Metadata only The coating performance of adipic acid modified and methacrylated bisphenol - A based epoxy oligomers(WILEY, 2007) KAHRAMAN, MEMET VEZİR; Bayramoglu, Guelay; Kahraman, M. Vezir; Kayaman-Apohan, Nilhan; Guengoer, AtillaIn the present work adipic acid modified and methacrylated bisphenol A based epoxy resins were prepared. The structures of oligomers were characterized by FT-IR. UV curable clear coatings were applied on aluminum substrates. The physical and mechanical properties of UV-cured coatings such as gel content, solvent resistance, hardness, gloss, flexibility and tensile tests were examined. In addition, the thermal behavior of coatings was also evaluated. It is observed that the tensile properties and thermal stabilities of modified epoxy methacrylate coatings mainly depend on the adipic acid content. The best results were obtained with 5 wt% adipic acid modification. Copyright (C) 2007 John Wiley & Sons, Ltd.Publication Metadata only N-vinylpyrrolidone/acrylic acid/2-acrylamido-2-methylpropane sulfonic acid based hydrogels: Synthesis, characterization and their application in the removal of heavy metals(ELSEVIER, 2007) KÖK YETİMOĞLU, ECE; Yetimoglu, E. Kok; Kahraman, M. V.; Ercan, O.; Akdemir, Z. S.; Apohan, N. KayamanIn this work, the synthesis of N-vinylpyrrolidone/acrylic acid/2-acryl amido-2-methylpropane sulfonic acid (NVP/AAc/ AMPS) based hydrogels by UV-curing technique was studied and their swelling behavior, heavy metal ion recovery capabilities were investigated. The structures of hydrogels were characterized by FT-IR analysis and the results were consistent with the expected structures. Thermal gravimetric analysis of hydrogels showed that the thermal stability of hydrogel decreases slightly with incorporation of AMPS units into the structure. In addition, the morphology of the dry hydrogel sample was examined by SEM. According to swelling experiments, hydrogels with higher AMPS content gave relatively higher swelling ratio compared to neat hydrogel. These hydrogels were used for the separation of Cd(II), Cu(II) and Fe(III) ions from their aqueous solutions. The influence of the uptake conditions such as pH, time and initial feed concentration on the metal ion binding capacity of hydrogel was also tested. The selectivity of the hydrogel towards the different metal ions tested was Cd(II) > Cu(II) > Fe(III). It was observed that the specific interaction between metal ions and ionic comonomers in the hydrogel affected the metal binding capacity of the hydrogel. The recovery of metal ions was also investigated in acid media. (c) 2007 Elsevier Ltd. All rights reserved.