Synthesis of orange-like Fe3O4/PPy composite microspheres and their excellent Cr(vi) ion removal properties

Abstract

Uniform orange-like Fe₃O₄/polypyrrole (PPy) composite microspheres have been synthesized using Fe₃O₄ microspheres as a chemical template under sonication. In the orange-like Fe₃O₄/PPy composite microspheres, the Fe₃O₄ particles played the role of “seeds” while the PPy was the “pulp and peel”. A growth mechanism for the orange-like Fe₃O₄/PPy composite microspheres was proposed in which partial pyrrole monomers are immersed into the gaps of Fe₃O₄ microspheres under sonication, meanwhile Fe³⁺ ions released from Fe₃O₄ microspheres in an acidic environment initiated the polymerization of pyrrole monomers in the interior or around the Fe₃O₄ microspheres, finally forming an orange-like structure. When used as an absorbent of Cr(VI) ions, the as-obtained Fe₃O₄/PPy microspheres showed strong adsorption capability with an adsorption capacity of about 209.2 mg g⁻¹, which is mainly attributed to the PPy “pulp and peel”. Furthermore, the magnetic Fe₃O₄ “seeds” in composite microspheres make them easy to separate from wastewater by magnetic separation.