Sorption of Chromium (VI) from an Aqueous Solution by a New Polymeric Resin Prepared by Gamma Radiation

A new polymeric resin poly(maleic acid –acrylamide )-Cesium P(MA-AM)-Cs was prepared by gamma radiation-induced co-polymerization of maleic acid ( MA) with acrylamide (AM) in the presence of cesium chloride CsCl as a metal salt in aqueous solution route at 25 KGy to be used as a sorbent. The polymeric resin was characterized using Fourier transform infra-red spectroscopy (FTIR), simultaneous thermogravimetry TGA, DTA differential gravimetric a nalysis and Scanning Electron Microscope (SEM). The data showed that the polymeric resin was thermally stable up to 481C. The sorption of Cr (VI) onto the prepared polymeric resin was investigated using batch equilibrium technique in relation to the pH, adsorbent weigh, initial concentration, contact time and temperature. The results showed that the adsorption capacity was highly pH-dependent and the maximum adsorption was attained from a solution as concentration of about 100 ppm at pH 2 with an adsorbent dosage of 0.05 g and contact time 30 minute at room temperature (25C). The adsorption capacity was found to be 74.6 mg/g at these specific conditions. Different models were tried to scan the surface of the exchanger. The sorption equilibrium data was fitted with Langmuir, Freundlish isotherm. The results indicated that the isotherm successfully fit the Langmuir adsorption isotherm. Lagergren-first –order and pseudo-second-order model were tested kinetically to describe the possible mechanism of the sorption process reaction. The experimental data fitted well with the pseudo-second-order kinetic model and the ion exchange mechanisms with controlled diffusion are predominates. In addition, thermodynamic parameters such as free energy (∆G°), enthalpy (∆H°) and entropy (∆S°) of the sorption were calculated. These parameters showed that the sorption of Cr (VI) onto the present polymeric material was spontaneous and endothermic in nature.