Graphene nanosheets decorated with tunable magnetic nanoparticles and their efficiency of wastewater treatment

Highlights: • Magnetic graphene/Fe₃O₄ nanocomposites were synthesized by a facile and fast one-pot method. • The sizes of Fe₃O₄ nanocrystals can be controlled by the weight ratio of GO to Fe₃O₄. • The graphene/Fe₃O₄ hybrid structures are highly efficient in purification of wastewater. • The decline in efficiencies of graphene/Fe₃O₄ is not more than 1.5% after five cycling runs. - Abstract: Magnetic graphene–Fe₃O₄ nanocomposites (G/Fe₃O₄) were fabricated by a facile and fast one-pot method and used as adsorbent to remove dye for wastewater using Rhodamine B as the adsorbate. Samples with different weight ratios of graphene oxide (GO) to Fe₃O₄ were prepared. The transmission electron microscopy results exhibit that the sizes of Fe₃O₄ nanocrystals decrease with the increasing of weight ratio of GO to Fe₃O₄. The magnetic characterization demonstrates that the saturation magnetization of nanocomposites decreases with the decreasing sizes of Fe₃O₄ nanocrystals. The investigation of adsorption kinetics and isotherm indicates the adsorption process can be described by Langmuir model and nanocomposites with the smaller sizes of Fe₃O₄ nanoparticles show better adsorption ability. Furthermore, the adsorbents could be recovered conveniently by magnetic separation and recyclable used after desorption process, and the decline in efficiencies of all samples is not more than 1.5% after five cycling runs