Adsorption removal of congo red onto magnetic cellulose/Fe3O4/activated carbon composite: Equilibrium, kinetic and thermodynamic studies

Magnetic cellulose/Fe3O4/activated carbon composites (m-Cell/Fe3O4/ACCs) were prepared successfully and characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The adsorption of congo red onto the novel m-Cell/Fe3O4/ACCs was studied as a function of contact time, initial concentration of congo red, adsorbent dosage, and pH of solution. The saturated magnetization of m-Cell/Fe3O4/ACCs reached 48.2 emu g(-1) and the magnetic adsorbent showed characteristics of super-paramagnetism, which indicated that m-Cell/Fe3O4/ACCs could be separated from treated solution by a magnetic process. A comparison of kinetic models showed that the overall adsorption process was best described by pseudo-second-order kinetic model. Thermodynamic analysis indicated an exothermic nature of adsorption and a spontaneous and favorable process. The m-Cell/Fe3O4/ACCs might be a promising candidate of high efficiency, low cost and convenient separation under magnetic field. (C) 2011 Elsevier B.V. All rights reserved.