Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
583699 | Journal of Hazardous Materials | 2008 | 9 Pages |
Abstract
In this study, a procedure for synthesis of new organic-inorganic magnetic composite resins was established. The procedure was based upon immobilization of magnetite (Mag) as a ferromagnetic material within the polymer poly(acrylic acid acrylonitrile) P(AA-AN) and the ion exchange resin (Amberlite IR120). The produced magnetic resins, IR120-PAN-Mag (R1) and P(AA-AN)-Mag (R2) were assessed as sorbents for Cr(VI). Various factors influencing the sorption of Cr(VI), e.g., pH, equilibrium time, initial concentration and temperature were studied. The sorption process was very fast initially and maximum sorption was achieved within 3 h and pH 5.1. The kinetic of the system has been evaluated with pseudo first order model, second order model, Elovich model, intra-particle diffusion model and liquid film diffusion model. Chromium interaction with composite particles followed second-order kinetics with a correlation coefficient extremely high and closer to unity and rate constant (ks) has the values 1.68 Ã 10â4 and 1.9 Ã 10â4 g (mgâ1 minâ1) for R1 and R2, respectively. The values of equilibrium sorption capacity (qe) are consistent with the modeled data and attain the range 893-951 mg gâ1. Kinetically, both pore diffusion and film diffusion are participating in ruling the diffusion of Cr(VI) ions. The sorption data gave good fits with Temkin and Flory-Huggins isotherm models. The isotherm parameters related to the heat of sorption are in the range 8-16 kJ molâ1 which is the range of bonding energy for ion exchange interactions and so suggest an ion exchange mechanism for removal of Cr(VI) by the composite sorbents. The adsorption process was exothermic with ÎH in the range of â73 to â97 kJ molâ1. The negative values of Gibbs free energy confirm the feasibility and the spontaneous nature of Cr(VI) removal with these novel composites.
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Authors
R.R. Sheha, A.A. El-Zahhar,