Facile solvothermal synthesis of Fe3O4/bentonite for efficient removal of heavy metals from aqueous solution

Abstract

Magnetic nanoparticles have attracted considerable attention due to their unique properties and versatile applications. Herein, we synthesized nanosized Fe3O4/bentonite nanocomposites (Fe3O4/Bents) by the facile one-step solvothermal method (200°C, 8.0h) using natural bentonite and ferric chloride as raw materials. The XRD, FTIR, TEM, SEM, BET, and VSM techniques were used to characterize the material and the results indicated that the Fe3O4/Bents exhibited nanosized and spherical shape with functional groups via the magnetic Fe3O4 orderly assembling on the surface of bentonite. The Fe3O4/Bents had superparamagnetism feature due to their higher magnetization saturation and lower remanence values. The surface area and total pore volume of the Fe3O4/Bents were all larger than the nature bentonite and pure Fe3O4. The feasibility of the as-synthesized Fe3O4/Bent-2.0 for removal of heavy metals (Pb2+, Cd2+ and Cu2+) from aqueous solution were also evaluated by batch equilibrium experiments. The kinetic and isothermal data well fitted the pseudo-second-order equation and Langmuir model, respectively. The adsorption reached equilibrium within 30min and the Langmuir maximum adsorption capacities of Fe3O4/Bent-2.0 were 81.5, 21.7 and 19.6mg/g for Pb2+, Cd2+ and Cu2+, respectively. Furthermore, the magnetic Fe3O4/Bents can be quickly and easily separated using a magnet before and after the adsorption process.