Unique magnetic graphene oxide with enhanced carboxylate functional groups for uranium separation by solid phase extraction

Abstract

The cation exchange capability of carboxylate functional group in graphene oxide is explored for uranium adsorption. The magnetic graphene oxide (MGO) composite was prepared from graphene oxide and magnetite (Fe3O4) to exercise magnetic separation of uranium from the aqueous phase. Characterization by XRD, Raman, SEM and TEM indicate fine aggregate of MGO in which Fe3O4 a dispersed between two GO layers. The proficiency of uranium adsorption in presence of major sea water constituents was probed by varying the pH, kinetics of adsorption, and uranium concentration. The kinetics of adsorption was found to fit into the pseudo-second-order model and the adsorption isotherm resembles Langmuir model. The proposed kinetic model demonstrates the predominant role of chemical reactions at the sites of adsorption over the diffusion of metal ions. The performance of MGO in adsorbing uranium, after several cycles of adsorption and recycling is found to be very promising for scaling up applications.