| dc.description.abstract | In this study, a fibrous adsorbent including double amidoxime groups were prepared by graft copolymerization of glycidyl methacrylate (GMA) onto poly (ethylene terephthalate) (PET) fibers by using benzoyl peroxide (Bz2O2) as initiator in aqueous solution. Then, GMA which grafted PET fibers were modified with iminodiacetonitrile (IDAN) in ethanol at 80 0C. Afterwards the nitrile groups were amidoximated by using hydroxylamine hydrochloride in methanol solution. The grafted and modificated fibers were characterized by fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and thermogravimetric analysis (TGA). The effect of important parameters such as pH, initial ion concentration, sorbent dosage, contact time and temperature on uptake of Cr (VI) ion was investigated. All adsorption experiments of Cr (VI) ions from aqueous solution onto chelating fibers were studied by using batch adsorption method. The results show that the adsorption amount of Cr (VI) ions increased with increasing initial ion concentration, contact time, temperature but decreased with increasing pH of the medium. The Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models were applied to explain the adsorption behavior. The adsorption isotherms of Cr (VI) on amidoximated fiber were well described by Langmuir isotherm and the maximum adsorption capacity calculated from Langmuir isotherm model was 125 mg/g. Thermodynamic parameters such as free energy (?G0), enthalpy (?H0) and entropy (?S0) were calculated.It has been observed that the amidoximated fibers are regenerable by 2M KOH and it is more selective for Cr (VI) ions in the mixed solution of Cr, Pb, Co, Ni, Cd, Cu at pH 2. | en_US |
