The synthesis of a manganese dioxide-iron oxide-graphene magnetic nanocomposite for enhanced uranium(VI) removal

In this study, we have developed a facile route for the fabrication of a manganese dioxide-iron oxide-reduced graphite oxide magnetic nanocomposite (MnO2-Fe3O4-rGO). The as-obtained nanomaterial (MnO2-Fe3O4-rGO) was characterized using transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, vibrating sample magnetometry, and Brunauer-Emmett-Teller surface area measurements. The MnO2-Fe3O4-rGO composite shows extraordinary adsorption capacity and fast adsorption rates for the removal of uranium(VI) in aqueous solution. The influence of factors including the dosage of the MnO2-Fe3O4-rGO composite used, pH of aqueous solution, and temperature were investigated. The thermodynamic parameters, including Gibbs free energy (Delta G degrees), standard enthalpy change (Delta H degrees) and standard entropy change (Delta S degrees) for the process, were calculated using the Langmuir constants. The results show that a pseudo-second-order kinetics model can be used to describe the uptake process using a kinetics test. Our present study suggests that the MnO2-Fe3O4-rGO composite can be used as a potential adsorbent for sorption of uranium(VI) as well as for providing a simple, fast separation method for the removal of uranium(VI) ions from aqueous solution.