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Öğe Adsorption of indole and 2-methylindole on ligand-exchange matrix(ACADEMIC PRESS INC ELSEVIER SCIENCE, 2004) Erciyes, N; Gurten, AA; Abdullah, MI; Ayar, AThe adsorption of indole and its 2-methyl derivative from aqueous solutions onto cobalt(II)-carboxylated diaminoethane sporopollenin (CDAE-sporopollenin) was studied using a fixed-bed column at 25 +/- 0.1 degreesC. Minicolumn adsorption studies showed that the breakthrough and the total adsorption capacities of CDAE-sporopollenin in the concentration range we have studied increased with increasing external ligand concentration. The characteristics of the adsorption process were investigated using Scatchard plot analysis, where the equilibrium binding data for indole on ligand exchanger gave rise to a linear plot. However, for 2-methylindole, divergence from the Scatchard plot was evident, consistent with the participation of secondary equilibrium effects in the adsorption process. The adsorption behaviors of ligands on CDAE-sporopollenin were expressed by both the Langmuir and Freundlich isotherms. The adsorption isotherm data for these ligands on the resin can be satisfactorily fitted to the Freundlich isotherm within the concentration range studied. However, in the case of 2-methylindole, the experimental data did not fit the Langmuir model, especially when a high ligand concentration range is used; this is probably due to the nonspecific interactions between the ligand exchange matrix and the methyl group present. Ligand adsorption constants and correlation coefficients for the ligands were calculated from the Langmuir and Freundlich isotherms. (C) 2004 Elsevier Inc. All rights reserved.Öğe Biosorption of nickel(II) and copper(II) ions from aqueous solution by Streptomyces coelicolor A3(2)(ELSEVIER SCIENCE BV, 2004) Ozturk, A; Artan, T; Ayar, AThe biosorption of nickel(II) and copper(II) ions from aqueous solution by dried Streptomyces coelicolor A3(2) was studied as a function of concentration, pH and temperature. The optimum pH range for nickel and copper uptake was 8.0 and 5.0, respectively. At the optimal conditions, metal ion uptake was increased as the initial metal ion concentration increased up to 250 mg l(-1). At 250 mg l(-1) copper(II) ion uptake was 21.8% whereas nickel(II) ion uptake was found to be as high as 7.3% compared to those reported earlier in the literature. Metal ion uptake experiments were carried out at different temperatures where the best ion uptake was found to be at 25 degreesC. The characteristics of the adsorption process were investigated using Scatchard analysis at 25 degreesC. Scatchard analysis of the equilibrium binding data for metal ions on S. coelicolor A3(2) gave rise to a linear plot, indicating that the Langmuir model could be applied. However, for nickel(II) ion, divergence from the Scatchard plot was evident, consistent with the participation of secondary equilibrium effects in the adsorption process. Adsorption behaviour of nickel(II) and copper(II) ions on the S. coelicolor A3(2) can be expressed by both the Langmuir and Freundlich isotherms. The adsorption data with respect to both metals provide an excellent fit to the Freundlich isotherm. However, when the Langmuir isotherm model was applied to these data, a good fit was obtained for the copper adsorption only and not for nickel(lI) ion. (C) 2004 Elsevier B.V. All rights reserved.Öğe Determination of the rate control step of chlorinated anilines in ligand exchange reactions on solid phase by using breakthrough technique(ELSEVIER SCIENCE BV, 2003) Ucan, M; Gurten, A; Ayar, AKinetic studies of chlorinated anilines as ligands on the cobalt(II)-carboxylated diaminoethyl-sporopollenin (CDAEsporopollenin) have been performed using continuous column runs. Adsorption rate measurements were carried out by using a UV-visible spectrophotometer, and rate control step of the reaction was determined. The adsorption of chlorinated anilines from solutions of different initial concentrations onto resin Was measured as a function of time at 25 degreesC. The initial ligand concentrations ranged from 6.0 x 10(-4) to 2.5 x 10(-3) mol l(-1). The results concerning the influence of the external solution concentration of the ligands upon the fractional attainment of equilibrium prove that the diffusion of the ligands into the resin beads plays an important role in the mechanism of the exchange reaction, although the exchange rate is chemical in its ultimate mechanism. A very fast initial adsorption resulting in an almost instantaneous attainment of the bulk of the equilibrium adsorption was followed immediately by a very slow rate of adsorption. In the case of 4- and 2,5-dichloroaniline, in all of the concentration range, the graphs of -ln[1 - U(alpha)] versus t were a straight line, which suggests that fractional attainment of equilibrium adsorption under film diffusion control is observed. On the contrary, 2- and 3-chloroaniline, the graphs were not a straight line and have underwent adsorption under particle diffusion control. (C) 2003 Elsevier Science B.V. All rights reserved.Öğe Determination of the rate control step of purin and pyrimidine bases adsorption on cobalt(II) - CDAE-sporopollenin(ELSEVIER SCIENCE BV, 2003) Ayar, A; Gurten, AAIn this work, adsorption kinetics of nucleic acid bases and nucleosides as ligands on cobalt(II)-carboxylated diaminoethyl sporopollenin (CDAE-sporopollenin) have been performed using continuous column runs. Adsorption rate measurements were carried out by using a-UV-Vis spectrophotometer, and rate control step of the adsorption process was determined. The adsorption of nucleic acid bases and nucleosides from solutions of different initial concentrations onto resin was measured as a function of time at 25degreesC. The results show that type of ligand has a great effect on ligand adsorption behaviour. External ligand concentrations play a significant role on adsorption rate of nucleic acid bases. The homogeneous diffusion model (HDM) is applied to the experimental breakthrough data. In all of the concentration range of adenine and uracil (nucleic acid bases), the graphs of -ln[l - U(alpha)] versus t were a straight line, which suggests that fractional attainment of equilibrium adsorption under film diffusion control is observed. On the contrary, adenosine and uridin (nucleosides), the graphs were not a straight line and have underwent adsorption under particle diffusion control. (C) 2003 Elsevier B.V. All rights reserved.Öğe Interaction of nucleic acid bases and nucleosides with cobalt ions immobilized in a column system(Elsevier Sci Ltd, 2006) Ayar, A; Mercimek, BThe interactions of ligands, such as adenine, adenosine, uracil and uridine with Co(II) ions immobilized by carboxylated diaminoethyl matrix on sporopollenin were investigated as a function of temperature by the breakthrough technique. The adsorption characteristics of ligands on Co(II)carboxylated diaminoethyl sporopollenin [Co(II)-CDAE-S] were investigated by Scatchard plot analysis under optimized conditions of flow rate and temperature. Equilibrium binding data used in Scatchard plot analysis for adenosine gave rise to a linear plot, indicating the presence of specific interaction and Langmuirean behavior. However, the adsorption of uracil on this ligand-exchange stationary phase was affected by the electrostatic or hydrophobic interaction in the whole concentration range. In the case of adenine and uridine, the adsorption performance was strongly affected by the initial ligand concentration. At high concentration, adenine and uridine were adsorbed specifically to the ligand exchanger matrix exposed on the adsorbent. At lower concentrations, the binding to the second sets of adsorbent was appeared because of nonspecific interaction such as hydrophobic and electrostatic. (c) 2006 Elsevier Ltd. All rights reserved.Öğe Ligand adsorption of adenine and adenosine on poly(vinyl chloride) bound cobalt(II)-carboxylated diaminoethyl complex(ELSEVIER SCIENCE BV, 2003) Ozdere, G; Kurt, G; Mercimek, B; Ayar, ALigand adsorption of adenine and adenosine has been studied by using cobalt(II)-poly(vinyl chloride) carboxylated diaminoethyl (PVC-CDAE) resin. Column runs were conducted to study the performance of the ligand exchanger. The adsorption of adenine and adenosine from solutions of different initial concentrations onto resin was measured using by breakthrough technique at 25 degreesC. The ligand concentration was chosen to be 0.0125-0.2 mmol l(-1). The characteristics of the adsorption process were investigated by using Scatchard plot analysis (q/C versus q). And the adsorption behaviour of these ligands on cobalt(II)-PVC-CDAE is expressed by the Langmuir and Freundlich isotherms. The adsorption data with respect to all ligands provide an excellent fit to the Freundlich isotherm, giving correlation coefficients in the range of 0.95-0.99 for the Freundlich isotherm. On the contrary, when the Langmuir isotherm model was applied to these data, a good lit was not obtained for the high ligand concentrations. (C) 2003 Elsevier B.V. All rights reserved.Öğe Removal of aniline from aqueous solution by PVC-CDAE ligand-exchanger(ELSEVIER SCIENCE BV, 2005) Gurten, AA; Ucan, S; Ozler, MA; Ayar, AThe adsorption of aniline from aqueous solutions onto cobalt(II)-poly(vinyl chloride)-carboxylated diaminoethane (PVC-CDAE) resin has been studied using a mini-column apparatus at 25 +/- 0.1 degrees C. First of all, experimental data obtained from the breakthrough curves were tested by using the Scatchard plot analysis, to have a preliminary prediction about the types of interaction of the resin with aniline. Our aim was to determine the model which best describes the experimental data. The aspect of the Scatchard plot indicated that the aniline adsorption did not follow the Langmuir model and the presence of two types of binding sites for aniline on the resin. However. the dynamics of aniline uptake were represented by the Freundlich model reasonably well. The kinetics of aniline adsorption from aqueous solution on the cobalt(II)-PVC-CDA-E have also been tested using continuous column runs and rate-controlling step of the process was determined. In this study, homogeneous diffusion model was adapted to a column system to describe the change in the aniline concentration at the column exit begining from breakthrough point as a function of time. Kinetic studies revealed that the rate-controlling step of the aniline adsorption was predominately film diffusion controlled rather particle diffusion. (c) 2005 Elsevier B.V. All rights reserved.Öğe Selective extraction of iron(III) from aqueous nitrate solution in the presence of cobalt(II), copper(II) and nickel(II) ions using BiS(Delta(2)-2-imidazolinyl)-5,5 '-dioxime(JAPAN SOC ANALYTICAL CHEMISTRY, 2004) Teke, M; Mercimek, B; Ozler, MA; Ayar, AThe feasibility of using bis(Delta(2)-2-imidazolinyl)-5,5'-dioxime (H2L) for the selective extraction of iron(III) from aqueous solutions was investigated by employing an solvent-extraction technique. The extraction of iron(III) from an aqueous nitrate solution in the presence of metal ions, such as cobalt(II), copper(II) and nickel(II), was carried out using H2L in binary and multicomponent mixtures. Iron(III) extraction has been studied as a function of the pH, equilibrium time and extractant concentration. From the extracted complex species in the organic phase, iron(III) was stripped with 2 M HNO3, and later determined using atomic-absorption spectrometry. The extraction was found to significantly depend on the aqueous solution pH. The extraction of iron(III) with H2L increases with the pH value, reaching a maximum in the zone of pH 2.0, remaining constant between 2 and 3.5 and subsequently decreasing. The quantitative extraction of iron(III) with 5 x 10(-3) M H2L in toluene is observed at pH 2.0. H2L was found to react with iron(III) to form ligand complex having a composition of 1:2 (Fe:H2L).Öğe Sorption equilibria of chlorinated anilines in aqueous solution on resin-bound cobalt ion(Elsevier Science Bv, 2002) Uçan, M; Ayar, AStudies have been made of the sorption equilibria of chlorinated anilines in aqueous solution on ligand exchange resin. The chlorinated anilines used included 2-chloroaniline, 3-chloroaniline, 4-chloroaniline and 2,5-dichloroaniline. A mini-column apparatus was used to study sorption of chlorinated anilines onto ligand exchange resin. The experiments were conducted in a constant temperature at 25 +/- 0.1 degreesC. The sorption behaviour of these chlorinated anilines on Co(II)-loaded carboxylated diaminoethyl sporopollenin (CDAE-sporopollenin) can be expressed by the Langmuir and Freundlich isotherms. The characteristics of the sorption process were also investigated using Scatchard plot analysis (q/C vs. q). When the Scatchard plot showed a deviation from linearity, greater emphasis was placed on the analysis of the adsorption data in terms of the Freundlich model, in order to construct the adsorption isotherms of the ligand(s) at particular concentration(s) in solutions. Equilibrium binding data for ligands gave rise to a linear plot, indicating that the Langmuir model could be applied. Ligand adsorption constants, dissociation constant (K-d) and correlation coefficients for the ligands were calculated from Langmuir and Freundlich isotherms. (C) 2002 Elsevier Science B.V. All rights reserved.Öğe Sorption of purin and pyrimidine bases onto chelating resin(Elsevier Science Bv, 2002) Ayar, A; Yildiz, SLigand sorption of nucleic acid bases and nucleosides has been studied by using ligand exchanger sporopollenin. A mini-column apparatus was used to study sorption of nucleic acid bases and nucleosides onto ligand exchanger resin. The experiments were conducted in a constant temperature at 25 +/- 0.1 degreesC . The sorption isotherms of nucleic acid bases and nucleosides from aqueous solution onto the resin were investigated. The ligand concentration was chosen to be 0.0125-0.2 mmol l(-1). The performance of the ligand exchanger in continuous operation was studied by conducting column runs. Ligand sorption constants and correlation coefficients for the adenine, adenosine, uracil and uridine on the chelating resin were calculated from Langmuir as well as Freundlich plots. The sorption binding constant of the ligands increased in the following sequences: uracil < uridine < adenosine < adenine. Ligand sorption behavior of modified sporopollenin with respect to nucleic acid bases and nucleosides was investigated. (C) 2002 Elsevier Science B.V. All rights reserved.
