Graphene/Fe3O4@polypyrrole nanocomposites as a synergistic adsorbent for Cr(VI) ion removal

Novel hybrid nanocomposites constructed via anchoring the Fe3O4@polypyrrole nanospheres with hierarchical porous structure on graphene nanosheets (graphene/Fe3O4@polypyrrole, GFP) have been prepared, and characterized by using TEM, XRD, XPS, FT-IR and TGA. The large saturation magnetization of 12.4 emu g−1 allows fast and economic separation of the GFP from solution. Due to the synergic effect between graphene and Fe3O4@polypyrrole, the GFP exhibits excellent adsorption capability of 348.4 mg g−1 for Cr(VI) removal, which is much higher than the previously reported values of other magnetic nanomaterials. Furthermore, the GFP is stable and recyclable, retaining about 72.2% of the removal efficiency after six adsorption–desorption cycles. The adsorption isotherms and kinetics could be well simulated by the Langmuir and pseudo-second-order models respectively. The GFP nanocomposites could be a good candidate for efficient Cr(VI) removal from the wastewater.