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    Adsorptive removal of Methylene blue and Methyl orange from aqueous media by carboxylated diaminoethane sporopollenin: On the usability of an aminocarboxilic acid functionality-bearing solid-stationary phase in column techniques
    (ELSEVIER SCIENCE BV, 2007) Ayar, Ahmet; Gezici, Orhan; Kucukosmanoglu, Muhittin
    The adsorption phenomena of Methylene blue (MB) and Methyl orange (MO) on a carboxylated diaminoethane sporopollenin (CDAE-S) solid phase were investigated in a column arrangement by using breakthrough technique. The adsorption phenomena were evaluated using some common adsorption isotherm models and Scatchard plot analysis, and obtained results were interpreted for evaluating the usability of CDAE-S for removal, recovery and preconcentration of the studied dyes both at the laboratory and industrial scales. On the basis of Scatchard plot analysis, the interaction types between the CDAE-S and the studied dyes were criticized in terms of affinity phenomena. Thus, the usability of a biomacromolecule-derived material, CDAE-S, as a cheap, environmentally-friendly and effective solid-stationary phase exhibiting both cation-exchange and anion-exchange characteristics at the same time, is discussed through the present study. Besides, from the obtained results, the protonated CDAE-S, which functionally resembles an amino acid structure, are presented as a two-in-one solid- stationary phase, and its adaptability to common processes performed under column conditions is also drawn in detail. (C) 2006 Elsevier B.V. All rights reserved.
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    COMPETITIVE SORPTION CHARACTERISTICS OF HEAVY METAL IONS ON HUMUS-SOIL ZONES DEVOLOPED ON MUDSTONE AND SPILITE (HARZ FOREST, GERMANY)
    (STEF92 TECHNOLOGY LTD, 2015) Gurel, Ali; Ayar, Ahmet
    In order to evaluate the sorption behavior of Cd2+, Pb2+, and Cu2+ ions on humus rich O and E/EB soil zones of mudstone and spilite, batch equilibrium experiments were performed at 25 degrees C in competitive component adsorption systems. Heavy metal ions like Cd2+, Pb2+, and Cu2+ were selected for adsorption studies considering their contribution as toxic metals in the environment. The adsorption of the heavy metal ions was studied at different initial solute concentrations and pH levels. The initial metal concentrations ranged from 7.0 10(-3) to 1.0 10(2) mg/L. The adsorption isotherms were obtained and firstly, Scatchard plot analysis (q/C vs. q) was used to investigate the adsorption behavior of the metal ions. However, in the adsorption of metal ions, deviation from linearity in the plot of q/C versus q was observed, indicating the presence of multi-model interaction and non-Langmuirean behavior. The adsorption behavior of these metal ions on soil zones of spilite and mudstone was expressed by the Freundlich isotherms. Adsorption constants and correlation coefficients were calculated from Freundlich plots.
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    Competitive sorption characteristics of heavy metal ions on humus-soil zones devoloped on mudstone and Spilite (Harz forest, Germany)
    (International Multidisciplinary Scientific Geoconference, 2015) Gürel, Ali; Ayar, Ahmet
    In order to evaluate the sorption behavior of Cd2+, Pb2+, and Cu2+ions on humus rich O and E/EB soil zones of mudstone and spilite, batch equilibrium experiments were performed at 25oC in competitive component adsorption systems. Heavy metal ions like Cd2+, Pb2+, and Cu2+were selected for adsorption studies considering their contribution as toxic metals in the environment. The adsorption of the heavy metal ions was studied at different initial solute concentrations and pH levels. The initial metal concentrations ranged from 7.0 10-3to 1.0 102mg/L. The adsorption isotherms were obtained and firstly, Scatchard plot analysis (q/C vs. q) was used to investigate the adsorption behavior of the metal ions. However, in the adsorption of metal ions, deviation from linearity in the plot of q/C versus q was observed, indicating the presence of multi-model interaction and non-Langmuirean behavior. The adsorption behavior of these metal ions on soil zones of spilite and mudstone was expressed by the Freundlich isotherms. Adsorption constants and correlation coefficients were calculated from Freundlich plots. © SGEM2015 All Rights Reserved.
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    Effect of the temperature and mobile phase composition on the retention behavior of nitroanilines on ligand-exchange stationary phase
    (ELSEVIER SCIENCE BV, 2006) Gurten, A. Ali; Ucan, Mustafa; Abdullah, Meysun I.; Ayar, Ahmet
    This paper deals with the separation of isomers of nitroaniline by liquid chromatography using the ligand-exchange technique. The chromatographic separations were performed on the ligand-exchanger sporopollenin. The sporopollenin used as support of stationary phase was modified with carboxylated-ethylenediamine matrix and was loaded with cobalt(II) ions. Using the column packed with cobalt(II) loaded carboxylated diaminoethyl sporopollenin [Co(II)-CDA-E-S], the retention behavior of 3- and 4-nitroanilines was investigated. The mobile phase used, was a mixture of 0.05 M NH4OH in ethanol-water. The resolution was strongly affected by the presence of ammonium hydroxide in the mobile phase and a concentration of 0.05 M was shown to be necessary for the separation of analytes. To study the effects of temperature on the resolution. column runs were also performed at various temperatures (15-60 degrees C). With increasing temperature. a decreased interaction between the solutes and the ligand-exchanger was observed. Consequently. the best results were obtained using a mixture of 0.05M NH4OH in ethanol-water (10:90. v/v) as the mobile phase at a column temperature of 35 degrees C. Ligand-exchange chromatography on the Co(II)-CDAE-S could be a useful alternative method for the separation of nitroaniline. (c) 2005 Elsevier B.V. All rights reserved.
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    Kinetics of diffusion-controlled adsorption of adenine and adenosine in a carboxymethyl diaminoethane PVC-mediated column system
    (SCIENCE REVIEWS 2000 LTD, 2015) Ayar, Ahmet
    The adsorption kinetics of adenine and adenosine on a ligand-exchange matrix, carboxymethyl diaminoethane poly(vinyl chloride) in cobalt form (cobalt-CMEDA-PVC), have been studied in a fixed-bed column system. The initial ligand concentrations ranged between 1.25x10(-5) and 2.0x10(-4) mol L-1. The kinetic studies were carried out spectrophotometrically, in order to determine the rate-controlling step of the adsorption. The kinetic data of the single-component systems were acquired from the breakthrough curves of the ligands on the basis of the equivalent points method. In this study, the homogeneous diffusion model was adapted to a fixed-bed column system to describe the differentiation in the ligand concentration of the effluent, beginning from breakthrough point as a function of time. The results obtained for the adsorption kinetics indicated that the diffusion step plays a significant role in the adsorption kinetics of the ligands, due to the fact that the adsorption performance was strongly affected by the initial concentration of ligands.
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    Ligand Exchange Chromatography of Nitrophenol Positional Isomers on Co-CMEDA-Silica Gel
    (WILEY-BLACKWELL, 2016) Ayar, Ahmet
    Nitrophenols are common pollutants detected in industrial effluents because they are used as basic raw materials in various industrial processes. Due to their toxicity to living things they are chemical species that need to be constantly monitored. Hence, the separation of nitrophenol isomers is very important to determine their levels in the environment. Since technical p-nitrophenol is contaminated with m-nitrophenol and the other aromatic compounds, the selective separation of p-nitrophenol from undesired impurities has become one of the important issues of the paracetamol synthesis. In the present work, a new chromatographic method for the separation of nitrophenol isomers on Co(II)-tris(carboxymethyl)ethylenediamine-silica gel (Co-CMEDA-Silica gel) has been developed using high performance liquid chromatography (HPLC). The chromatographic conditions were optimized by studying the effects of mobile phase composition. The positional isomers of nitrophenol (o-, m-, and p-nitrophenol) could be separated by using ternary mobile phases with water/methanol/acetonitrile in the ratio 5: 20: 75 under isocratic conditions. The baseline separation of nitrophenol isomers has been achieved successfully with the stepwise gradient elution.
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    On the removal of some phenolic compounds from aqueous solutions by using a sporopollenin-based ligand-exchange fixed bed - Isotherm analysis
    (ELSEVIER SCIENCE BV, 2008) Ayar, Ahmet; Gursal, Selpic; Gurten, A. Ali; Gezici, Orhan
    Single component adsorption of phenol and 2-, 3- and 4-nitrophenol from water was studied under dynamic column conditions by using a carboxymethyl diaminoethane sporopollenin in a cobalt ion-loaded form, Co(II)-CDAE-S, as solid phase. Adsorption isotherm data were acquired by frontal analysis for five plateau concentrations ranged from 1.25 x 10(-5) to 2.00x 10(-4) mol l(-1). The studied ligand-exchange sporopollenin resin showed a selective adsorptive nature within the group of studied nitrophenols, and the nature of phenols' adsorption on the Co(II)-CDAE-S was analyzed in terms of specific bindings by using Scatchard plot analysis. In light of the Scatchard plot analysis, the adsorption of examined compounds was mainly attributed to the specific bindings based on the ligand-exchange matrix of the studied adsorbent. The nitro-substituted phenols were found to be less strongly adsorbed than the phenol, and both binding strength and theoretical saturation capacity had an obvious relationship with the position of nitro substituent: The theoretical saturation capacities calculated from applied isotherm models exhibited an increase in the order of phenol < 4-nitrophenol < 3-nitrophenol < 2-nitrophenol, whereas a reverse order was showed for binding strengths.
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    Sorption behavior of Cu(II) ions on insolubilized humic acid under acidic conditions: An application of Scatchard plot analysis in evaluating the pH dependence of specific and nonspecific bindings
    (ELSEVIER SCIENCE BV, 2007) Gezici, Orhan; Kara, Huseyin; Ayar, Ahmet; Topkafa, Mustafa
    Sorption behavior of Cu(II) ions on a humic acid-based solid phase, insolubilized humic acid (IHA), were investigated under continuous column conditions. The quantitative data were derived on the basis of breakthrough curves obtained at different experimental conditions. For the studied experimental conditions, the highest and lowest observable capacities of IHA toward Cu(II) were found as 48.34 and 0.84 mu mol g(-1), respectively. In order to evaluate the pH dependence of Cu(II) binding on IHA, the effect of influent concentration was investigated at three different pH values (1.0, 2.0 and 3.0), and adsorption isotherms were derived for each acidic condition. The characteristics of Cu(II) bindings were evaluated by using Scatchard plot analysis, and it was observed that under strongly acidic condition, pH 1.0, nonspecific and/or multi-type interactions between Cu(II) and MA were the prevailing effects causing the Cu(II) sorption. On the other hand, at pH 2.0 and 3.0, the role of specific interactions was more clearly observed, and so at pH(s) 2.0 and 3.0, the binding of Cu(II) on IHA was mainly attributed to specific interactions rather than nonspecific ones. For pH 2.0 and 3.0, the binding types of Cu(II) on IHA were sub-classified according to different affinities observed between Cu(II) and IHA, and thus two main types of specific bindings were proposed for the studied influent concentration range (1.0 x 10(-3) to 1.0 X 10(-1) mol l(-1)): Type-1, high-affinity/low capacity and Type-2, low-affinity/high capacity bindings. Finally, probable benefit of each specific binding type in separation of Cu(II) from acidic aqueous media has been discussed in detail. (c) 2006 Elsevier B.V. All rights reserved.
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    Stepwise Frontal Analysis to Derive Equilibrium Sorption Data for Copper and Aniline on Functionalized Sporopollenin
    (WILEY-BLACKWELL, 2009) Gezici, Orhan; Ayar, Ahmet
    A dynamic method called stepwise frontal analysis (SFA) was Used to derive equilibrium sorption data of copper and aniline on a carboxylated diaminoethane sporopollenin (CDAE-S) solid phase. The derived data wits modeled on the basis of some common adsorption isotherms, and the importance of Scatchard plot analysis in isotherm modeling was emphasized. In light of the applied isotherm models, the role of aminocarboxylic acid functionalities in the sorption of each chemical species was discussed in terms of specific and nonspecific binding.
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    The adsorption behavior of crystal violet in functionalized sporopollenin-mediated column arrangements
    (ACADEMIC PRESS INC ELSEVIER SCIENCE, 2006) Gezici, Orhan; Kucukosmanoglu, Muhittin; Ayar, Ahmet
    The adsorption behavior of Crystal Violet (CV) on a sporopollenin-based solid phase, carboxylated diaminoethane sporopollenin (CDAE-S), was investigated under column conditions, and the obtained breakthrough profiles were used in evaluations and quantifications. The adsorption capacity of the CDAE-S was observed to be considerably higher than that of diaminoethane sporopollenin (DAE-S), revealing the importance of electrostatic interactions and carboxyl groups in the adsorption of CV on the CDAE-S. The binding of CV on the DAE-S was found to be a typical nonspecific adsorption, whilst cation-exchange was proposed as the main mechanism for monolayer adsorption of CV on the CDAE-S. Hence in the present study, the cation-exchange is suggested as an effective process for removal and recovery of CV from aqueous effluents, and in view of the pH point of zero charge matter, multifunctionality of the CDAE-S is discussed in detail, and various application possibilities based on "aminocarboxylic acid" functionality are also drawn. (c) 2006 Elsevier Inc. All rights reserved.
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    The adsorption behaviors of Methylene Blue and Methyl Orange in a diaminoethane sporopollenin-mediated column system
    (ELSEVIER SCIENCE BV, 2006) Kucukosmanoglu, Muhittin; Gezici, Orhan; Ayar, Ahmet
    The adsorption behaviors of Methylene Blue and Methyl Orange on a diaminoethane sporopollenin (DAE-S) solid phase were investigated in a column arrangement, and breakthrough profiles were used in evaluations and quantifications. The adsorption behaviors were evaluated using some common adsorption isotherm models and Scatchard plot analysis. The results showed that the DAE-S was useful for abstracting anionic dyes from cationic dyes. Thus, the usability of a biopolymer derived material (DAE-S) as a cheap, environmentally friendly and effective solid/stationary phase is discussed through the present study, and the adaptability of the DAE-S to common processes performed under column conditions is also drawn in detail. (c) 2006 Elsevier B.V. All rights reserved.