Removal of Cd2+ and Cu2+ ions from aqueous solution by using Fe–Fe3O4/graphene oxide as a novel and efficient adsorbent

The nano Fe–Fe3O4/graphene oxide (GO) was successfully synthesized by the precipitation method and followed by chemical reduction using FeCl3 as iron sources and NaBH4 as reducing agent. The products were characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy, transmission electron microscopy (TEM), BET, x-ray photoelectron spectroscopy (XPS) and VMS. From the obtained XRD and XPS results, it revealed the formation of both Fe and Fe3O4 nano particles on GO surface. TEM images showed that both Fe3O4/GO and Fe–Fe3O4/GO had small particle size of 10–20 nm and uniform size distribution. Fe3O4/GO and Fe–Fe3O4/GO were used as adsorbents for removal of Cd2+ and Cu2+ ions from aqueous solution. Maximum adsorption capacity (Qmax) of Fe–Fe3O4/GO for Cu2+ and Cd2+ are 90.0 mg g−1 and 108.6 mg g−1, respectively. These values are much higher as compared to those of Fe3O4/GO as well as those reported in the literature. Additionally, this novel adsorbent can be reused by washing with diluted Hcl solution and easily recovered by applying the magnetic field. The Cd2+ adsorption isotherm fits better for the Langmuir model that of the Freundlich model and it obeys the pseudo-second order kinetic equation.