Preparation, characterization and application of magnetic Fe3O4-CS for the adsorption of orange I from aqueous solutions.

Fe3O4 (Fe3O4-CS) coated with magnetic chitosan was prepared as an adsorbent for the removal of Orange I from aqueous solutions and characterized by FTIR, XRD, SEM, TEM and TGA measurements. The effects of pH, initial concentration and contact time on the adsorption of Orange I from aqueous solutions were investigated. The decoloration rate was higher than 94% in the initial concentration range of 50-150 mg L(-1) at pH 2.0. The maximum adsorption amount was 183.2 mg g-1 and was obtained at an initial concentration of 400 mg L(-1) at pH 2.0. The adsorption equilibrium was reached in 30 minutes, demonstrating that the obtained adsorbent has the potential for practical application. The equilibrium adsorption isotherm was analyzed by the Freundlich and Langmuir models, and the adsorption kinetics were analyzed by the pseudo-first-order and pseudo-second-order kinetic models. The higher linear correlation coefficients showed that the Langmuir model (R(2) = 0.9995) and pseudo-second-order model (R(2) = 0.9561) offered the better fits.