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Öğe Adsorption behavior of copper(II) ion from aqueous solution on methacrylic acid-crafted poly(ethylene terephthalate) fibers(John Wiley & Sons Inc, 2000) Coskun, R; Yigitoglu, M; Sacak, MThe adsorption behavior of methacrylic acid-grafted poly(ethylene terephthalate) fibers was studied toward the copper(II) ion in aqueous solutions by a batch equilibriation technique. The influence of treatment time, temperature, pH of the solution, metal ion concentration, and graft yield were considered. One hour of adsorption time was found sufficient to reach adsorption equilibrium for the copper(II) ion. It was found that the adsorption isotherm of Cu(II)fits Langmuir-type isotherms. The adsorption process is not affected by the temperature when treated with low ion concentration, but is remarkably decreased at a high ion concentration. The heat of adsorption value was calculated as 0.71 kcal/mol. It was found that the reactive fibers are stable and regenerable by acid without losing their activity. (C) 2000 John Wiley & Sons.Öğe Adsorption of copper(II), cobalt(II), and iron(III) ions from aqueous solutions on poly(ethylene terephthalate) fibers(John Wiley & Sons Inc, 1998) Yigitoglu, M; Ersoz, M; Coskun, R; Sanli, O; Unal, HIThe adsorption behavior of poly(ethylene terephthalate) (PET) fibers towards copper(II), cobalt(II), and iron(III) ions in aqueous solutions was studied by a batch equilibriation technique. Influence of treatment time, temperature, pH of the solution, and metal ion concentration on the adsorption were investigated. Adsorption values for metal ion intake followed the following order: Co(II) > Cu(II) > Fe(III). One hour of adsorption time was found sufficient to reach adsorption equilibrium for all the ions. The rate of adsorption was found to decrease with the increase in the temperature. Langmuir adsorption isoterm curves were found to be significant for all the ions studied. The heat of adsorption values were calculated as -5, -2.8, and -3.6 kcal/mol for Cu(II), Co(II), and Fe(III) ions, respectively. (C) 1998 John Wiley & Sons, Inc.Öğe Adsorption of hexavalent chromium from aqueous solutions using 4-vinyl pyridine grafted poly(ethylene terephthalate) fibers(Springer, 2005) Yigitoglu, M; Arslan, MSorption of hexavalent chromium ions from aqueous solution by 4- vinyl pyridine (4-VP) grafted poly(ethylene terephthalate) (PET) fibers was studied. The Influences of adsorption time, pH of solution and Cr(VI) concentration on the adsorbed amount were investigated. 30 minutes of treatment time was found to be sufficient to reach equilibrium. pH 3.0 was found as the optimum pH value in the process. The maximum adsorption capacity of the material (k(s)) was found to be 263.16 mg g(-1). It was found that the reactive fibers are stable and regenerable by acid or base without losing their activity.Öğe Controlled release of Aldicarb from carboxymethylcellulose microcapsules(Scientific Technical Research Council Turkey, 1997) Arica, MY; Yigitoglu, M; Lale, M; Kok, FN; Hasirci, VSodium carboxymethyl cellulose was converted into microspheres by crosslinking with aluminum chloride. Various microsheres with different amounts of crosslinker, biopolymer of various concentrations and molecular weights, and with different pesticide (Aldicarb) contents and pesticide to polymer ratios were prepared. The pesticide encapsulation efficiencies and aldicarb release kinetics of the resultant microcapsules were investigated. It was possible to modify the release behaviour by varying the above parameters and to have drug release with half-lives longer than 100 hours in aqueous media. The release kinetics were described by first order and zero order kinetics.Öğe Graft copolymerization of n-vinyl-2-pyrrolidone on dimethyl sulfoxide pretreated poly(ethylene terephthalate) films using azobisisobutyronitrile initiator(John Wiley & Sons Inc, 1997) Unal, HI; Coskun, R; Sanli, O; Yigitoglu, MPoly(ethylene terephthalate) (PET) films were grafted with n-vinyl-2-pyrrolidone (n-VP) using an azobisisobutyronitrile (AIBN) initiator. Films were pretreated in dimethyl sulfoxide (DMSO) for 1 h at 140 degrees C before the polymerization reaction was carried out. Variations of graft yield with time, temperature, initiator, and monomer concentrations were investigated. The optimum temperature and polymerization time was found to be 70 degrees C and 4 h, respectively. Increasing monomer concentration from 0.28 to 1.22M and initiator concentration from 1.77 x 10(-3) to 4.20 x 10(-3)M enhanced the percent grafting. The effects of monomer and initiator diffusion on PET films were also studied. The overall activation energy for grafting was calculated as 11.5 kcal/mol. Further changes in properties of PET films such as water-absorption capacity and intrinsic viscosity mere determined. The grafted films were characterized with FTIR and scanning electron microscopy (SEM). (C) 1997 John Wiley & Sons, Inc.Öğe Kinetic study of ligand exchange reaction of anions as ligands on DAE-sporopollenin(Academic Press Inc Jnl-Comp Subscriptions, 1996) Ersoz, M; Vural, US; Yigitoglu, M; Sezgin, MThe specific rate coefficients and ligand sorption isotherms of Br and I- as ligands on diaminoethyl-sporopollenin were determined as a function of pH and temperature between 20 and 60 degrees C. The ligand exchange rates were measured just after the rapid mixing of the ligand solution with the resin suspension. The data have also been analyzed to obtain activation parameters Delta G, Delta H, and Delta S for reaction in the corresponding mixture. A single ligand-exchange process was observed; the sorption of ligand increased with decreasing pH and hydrated radius of ligands and increasing temperature. A reaction mechanism which describe the ligand exchange reaction is proposed. (C) 1996 Academic Press, Inc.Öğe The study of kinetic models for ligand exchange of anions as ligands using ligand-exchange resin(John Wiley & Sons Inc, 1997) Ersoz, M; Yigitoglu, M; Ayar, AA comparative study of kinetic models for ligand exchange of I- --> Cl- and Br- --> Cl- as ligands as a function of pH and concentration using diaminoethyl-sporopollenin (DAE-sporopollenin) resin were investigated during the ligand-exchange reaction of the liquid phase. A batch technique was employed for the study of the kinetics of I and Br/Cl exchange as ligands. Five kinetic models were applied to the experimental data. The rate of ligand exchange was increased with decreasing of the hydrated ionic radius and pH. The curve fitting of the mathematical models and the behavior of the kinetic curves are discussed for direct ligand exchange under the conditions employed. (C) 1997 John Wiley & Sons, Inc.
