Dispersedly embedded loading of Fe3O4 nanoparticles into graphene nanosheets for highly efficient and recyclable removal of heavy metal ions

The regulated loading of Fe3O4 nanoparticles (NPs) into a graphene nanosheet (NS) matrix along with the process of reducing graphene oxide (GO) has been achieved via a facile hydrothermal self-assembly strategy. The optimized graphene/Fe3O4 (GE) composite with dispersedly embedded hybridization which yields a high surface area serving as active adsorption sites and providing effective protection of the Fe3O4 NPs against release, aggregation, oxidation or dissolution in wastewater, as well as stable superparamagnetism allowing fast magnetic recycling. It exhibits fast Cr(vi) removal with a high adsorption capacity in acidic and neutral solutions, and the adsorption kinetics follow the pseudo-second-order model in accordance with the chemisorption in nature. Moreover, the adsorption performance shows a broad-spectrum universality to various heavy metal ions including Fe(III), Cu(II), Cd(II), etc. and has recyclability after pH-manipulated desorption, thus the GE composite has been demonstrated as a promising separable adsorbent for removing heavy metals from wastewater.