Preparation of polydopamine-functionalized graphene-Fe3O4 magnetic composites with high adsorption capacities

In the present study, we report a simple solution mixing method to prepare polydopamine-functionalized graphene-Fe3O4 (DGF) nanocomposites with high adsorption capacities and an easy-separation ability. Water-soluble Fe3O4 particles are firmly deposited onto the surfaces of graphene oxide (GO) via electrostatic and hydrogen interactions. The interaction between the GO and Fe3O4 particles can prevent the graphene nanosheets from restacking and the Fe3O4 particles from agglomeration. The introduction of dopamine to functionalize GO not only reduces the GO but also endows abundant chemical groups. The existence of polydopamine affords more active sites for adsorption and further enhances the interaction of the GO and Fe3O4 particles to obtain adsorbent materials with stable structures. The adsorption capacity of DGF nanocomposites for methylene blue (MB) is 365.39 mg g(-1), which is much higher than that of graphene-Fe3O4 (GF) nanocomposite. Simultaneously, the DGF nanocomposites can be easily removed from polluted water after adsorption for MB by using a magnetic field, which is highly important for water conservation.