Design of three-dimensional macroporous reduced graphene oxide–Fe3O4 nanocomposites for the removal of Cr(VI) from wastewater

Three-dimensional macroporous reduced graphene oxide–Fe3O4 nanocomposites (3D macroporous rGO–Fe3O4 nanocomposites) were synthesized through electrostatic self-assembly method. The morphology and structure characteristics of 3D macroporous rGO–Fe3O4 nanocomposites were studied in detail. Then 3D macroporous rGO–Fe3O4 nanocomposites were used as adsorbents for the removal of Cr(VI) from wastewater. The effects of contact time and solution pH on the adsorption properties of 3D macroporous rGO–Fe3O4 nanocomposites were also investigated. Due to the hierarchical porous structure, high surface area and large pore volume, 3D macroporous rGO–Fe3O4 nanocomposite adsorbents exhibited excellent adsorption capability and rapid adsorption rates for Cr(VI) from aqueous solution. The kinetic and isothermal studies suggested that the adsorption process could be best described by pseudo-second-order kinetic model and Langmuir isotherm model, respectively. Moreover, the adsorbents could be separated easily by an external magnetic field for reusability, demonstrating great potential for the treatment of wastewater containing Cr(VI) during practical applications.