Person: KAHRAMAN, MEMET VEZİR
Loading...
Email Address
Birth Date
Research Projects
Organizational Units
Job Title
Last Name
KAHRAMAN
First Name
MEMET VEZİR
Name
8 results
Search Results
Now showing 1 - 8 of 8
Publication Metadata only Removal of Ag(I) from Aqueous Solutions by Thiol-ene-Based Hydrogel and Its Application to Radiographic Films(SPRINGER, 2014) KÖK YETİMOĞLU, ECE; Firlak, Melike; Kahraman, Memet Vezir; Yetimoglu, Ece KokThe thiol-ene-based P(Penta3MP4/PEGDA/AAc) hydrogels were prepared by UV curing technique, then characterized and used as adsorbents for the investigation of the effect of process parameters such as pH of solution, contact time, and initial concentration of solution, on the removal of Ag(I) from aqueous solution. The results indicate that the adsorption of Ag(I) ions from aqueous solutions is strongly dependent on pH under experimental conditions. Both Langmuir and Freundlich isotherm models were applied to experimental data, and the results show that the adsorption process is well fitted to the Langmuir isotherm model. Selectivity, reusability, and applicability of hydrogels to radiographic film waste were investigated.Publication Metadata only Preparation and characterization of sol-gel hybrid coating films for covalent immobilization of lipase enzyme(ELSEVIER, 2016) OGAN, AYŞE; Yuce-Dursun, Basak; Cigil, Asli Beyler; Dongez, Dilek; Kahraman, M. Vezir; Ogan, Ayse; Demir, SerapIn this study UV-curable hybrid epoxy-silica polymer films were prepared via sol-gel method. Lipase (EC 3.1.1.3) from Candida rugosa was covalently immobilized onto hybrid epoxy-silica polymer films and immobilization capacity of polymer films was found 7.22 mg g(-1). The morphology of the polymeric support was characterized by scanning electron microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Immobilized and free enzymes were used in two different reaction systems: hydrolysis of p-nitrophenyl palmitate in aqueous medium and synthesis of p-nitrophenyl linoleate (from p-nitrophenol and linoleic acid) in n-hexane medium. The effect of temperature on hydrolytic and synthetic activities was investigated and observed maximum activities at 50 degrees C and 45 degrees C for immobilized enzyme, orderly. Km values for free enzyme were determined 0.71 and 1.12 mM by hydrolytic and synthetic activity assays, respectively, while these values were observed as 0.91 mM and 1.19 mM for immobilized enzyme. At the end of 30 repeated cycles, 56% and 59% of initial activities remained for hydrolytic and synthetic assays, respectively. Native enzyme lost its activity completely within 20 days, whereas the immobilized enzyme retained for hydrolytic and synthetic activities was approximately 82% and 72%, respectively, under the same storage time. (C) 2016 Elsevier B.V. All rights reserved.Publication Metadata only Cellulose/cysteine based thiol-ene UV cured adsorbent: removal of silver (I) ions from aqueous solution(SPRINGER, 2021) BİRTANE, HATİCE; Cigil, Asli Beyler; Urucu, Oya Aydin; Birtane, Hatice; Kahraman, Memet VezirIn the present study, a novel, eco-friendly, and simple polymeric adsorbent was obtained from cellulose acetate butyrate (CAB) and cysteine (Cys) to remove silver (I) ions in the presence of a thiol-ene click reaction under UV rays. Accordingly, firstly, CAB was modified with acrylate groups to turn it into a photocurable resin. Then, the acrylate modified CAB obtained with the monomer having cysteine and triacrylate group was crosslinked by thiol-ene click reaction under UV rays to obtain an eco-friendly adsorbent. The adsorbent acquired -S-, -COO and -NH2 groups as a result of this reaction and these functional groups are known to have the ability to selectively couple with Ag(I) ions. The adsorbent was evaluated for the selective removal of Ag(I) ions from aqueous samples characterized by SEM, SEM-EDAX, and FTIR. To determine the most suitable conditions, the effect of important parameters such as pH and contact time was investigated. It was determined that the most suitable isotherm for adsorption was the Langmuir isotherm (R: 0.999). The efficacy of our eco-friendly adsorbent was investigated in a real stream and lake waters and very good results were achieved. [GRAPHICS] .Publication Metadata only Removal of Lead and Cadmium Ions from Aqueous Solutions Using Sulphur and Oxygen Donor Ligand Bearing Hydrogels(TAYLOR & FRANCIS INC, 2010) KÖK YETİMOĞLU, ECE; Firlak, Melike; Yetimoglu, Ece Koek; Kahraman, Memet Vezir; Apohan, Nilhan Kayaman; Deniz, SabahattinA new thiourea and urea functional monomers were synthesized. A series of hydrogels were prepared by photopolymerization. The hydrogels were used for the removal of Pb(II) and Cd(II) ions from aqueous solutions. The influence of the uptake conditions such as the pH, the time, and the initial feed concentration on the metal ion binding capacity of hydrogel was tested. The selectivity of the hydrogels towards the different metal ions was also tested. The adsorption isotherm models were applied. The limits of detection and quantification were calculated. The usability of the hydrogels for preconcentration studies were also investigated.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 Uptake of Pb2+ Using N-Vinyl Imidazole Based Uniform Porous Hydrogels(TAYLOR & FRANCIS INC, 2011) KÖK YETİMOĞLU, ECE; Firlak, Melike; Cubuk, Soner; Yetimoglu, Ece Kok; Kahraman, Memet VezirThe uniform porous and continuous phase lead (II) adsorbent hydrogel, was prepared by copolymerizing 2-hydroxyethyl methacrylate (HEMA), acrylic acid (AAc), and N,N'-methylenebisacrylamide (MBAAm), with n-vinyl imidazole (VIM). A series of hydrogels, including different ratios of VIM, were prepared by photopolymerization and characterized. The influence of the uptake conditions such as pH, functional monomer percent, contact time, initial feed concentration, and foreign metal ions on the metal ion binding capacity of hydrogel, were also tested. The selective chelation of heavy metal ions from synthetic wastewater was also studied. The affinity order on molar basis was observed as follows: Pb (II) > Zn (II) > Cd (II). Chelation behavior of heavy metal ions could be modelled using both the Langmuir and Freundlich isotherms and it was seen that the Langmuir isotherm model was the best fit for the adsorption of Pb (II) ions in P(VIM/AAc/HEMA) hydrogel. Moreover, the limits of detection and the quantification values were determined. Regeneration of the hydrogels was easily performed with 1M HCl and the same hydrogel can be reused five times almost without any loss of adsorption capacity. All these features make P(VIM/AAc/HEMA) hydrogels potential candidate adsorbent for heavy metal removal.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.Publication Metadata only Statistical optimization and selective uptake of Au(III) from aqueous solution using carbon nanotube-cellulose based adsorbent(ELSEVIER, 2022) BİRTANE, HATİCE; Birtane, Hatice; Urucu, Oya Aydin; Yildiz, Nilgun; Cigil, Asli Beyler; Kahraman, Memet VezirIn this study, a carbon nanotube cellulose-based UV-curable nanocomposite was prepared as an adsorbent to selectively separate Au (III) ions from an aqueous medium. For this purpose, thiol-functionalized carbon nanotube and acrylate-functionalized hydroxyethyl cellulose were synthesized and the photo-curable adsorbent was obtained using the thiol-ene click reaction. The FTIR spectra revealed that the thiol groups and acrylate groups were successfully attached to carbon nanotube and hydroxyethyl cellulose, respectively. Moreover, the Scanning Electron Microscopy-Energy Dispersive X-Ray analyses showed that the photo-curable adsorbent contained sulfur atoms, thus indicating successful modification. The parameters affecting the recovery of the Au (III) ions were determined using the Plackett-Burman method. The optimum values of the parameters, which were pH, adsorption time, initial Au (III) concentration, and adsorbent amount were determined using the Box-Behnken method. The Langmuir adsorption isotherm was determined to be the best equation to describe the interaction of the Au (III) ions with the adsorbent (R-2: 0.995). The examination of the effectiveness of the photocurable adsorbent in the presence of different metal ions yielded prosperous results. Also, the developed method has been successfully applied for the recovery of Au(III) ions in river waters.