Constructing carbon-coated Fe 3 O 4 hierarchical microstructures with a porous structure and their excellent Cr(VI) ion removal properties

A facile solvothermal method coupled with an annealing strategy is developed to synthesize Fe 3 O 4 /carbon (Fe 3 O 4 @C) magnetic composite microstructures with different morphologies, including flower-like, hollow spheres and egg-like. The unique multiporous and hollow structure of the as-prepared hierarchical Fe 3 O 4 @C hollow microsphere results in an appealing performance as an absorber of Cr(VI) ions in aqueous solution, delivering a high capacity of ~ 197.2 mg/g. Meanwhile, the magnetic Fe 3 O 4 ‘‘core’’ in the hierarchical microstructures can be easily separated from aqueous systems by magnetic separation. Furthermore, the carbon layers effectively prevent the aggregation of magnetic Fe 3 O 4 nanoparticles. The excellent absorbing ability of Cr(VI) ions and easy separation process strongly suggest that the Fe 3 O 4 @C magnetic microstructures would have a great potential as adsorbing materials in the large-scale application in environmental purification.