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 superparamagnetism, 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.

► The m-Cell/Fe3O4/ACCs prepared showed the characteristics of superparamagnetism. ► The m-Cell/Fe3O4/ACCs could be separated from the treated solution by a magnetic process. ► The thermodynamic analysis indicated an exothermic nature and a spontaneous and favorable process for congo red adsorption onto m-Cell/Fe3O4/ACCs. ► The m-Cell/Fe3O4/ACCs might be a promising candidate of high efficiency, low cost, and convenient separation under magnetic field.