Abstract
New polyamidoxime chelating resin (PAO-AN) was prepared by copolymerization of acrylonitrile (AN) with N,N′-methylenebisacrylamide (MBA) followed by amidoximation reaction with hydroxyl amine under alkaline conditions. The composition, properties and morphology of the resulting chelating resin have been characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis, scanning electron microscopy, surface area measurements and water regain. Batch technique was employed to examine the effects of different parameters such as solution pH, concentration of metal ions, contact time and medium temperature on metal ion uptake. The results indicated that the new chelating resin (PAO-AN) had high affinity towards heavy metal ions such as Cu(II), Ni(II) and Mn(II) which showed the maximum uptake of the chelating resin of 2.62, 2.21 and 1.42 mmol/g resin, respectively. The adsorption data have been perfectly described by Langmuir isotherm rather than other isotherms such as Freundlich and Temkin. Kinetics data have been analyzed using pseudo-first order, pseudo-second order, and intra-particle diffusion equations. However, pseudo-second-order kinetic model was best fit with the obtained data. Thermodynamic data proved the spontaneity of sorption process. Furthermore, the removal of metal ions using amidoxime resin (PAO-AN) has been studied using column technique as well. Regeneration was effectively performed using nitric acid and the chelating resin could be used repetitively for five times with little decrease (≈1–10%) in sorption of metal ions.