Functionalized hollow MnFe2O4 nanospheres: design, applications and mechanism for efficient adsorption of heavy metal ions

Abstract

The spread of heavy metal ions has given rise to severe environmental problems, and eliminating heavy metal pollutants from the environment has become a difficult task facing the world. Developing a new material with efficient adsorption of heavy metal ions has become a hot focus of the academic community recently. This work presents a L-cysteine functionalized magnetite hollow MnFe₂O₄ nanosphere (H-MnFe₂O₄-Cys) material used to remove heavy metal ions in water, and this could be mass-produced using carbonized MnFe₂O₄ as a matrix, mixed acid as etchant and L-cysteine as the modification agent in a process-controllable reactor. The morphology of H-MnFe₂O₄-Cys could be effectively controlled by adjusting the etching time. The possible mechanism of the synthesis of H-MnFe₂O₄-Cys and the efficiency of the removal of Cr⁶⁺ and Pb²⁺ were discussed in detail. Based on the high magnetism, large interior cavities, high porosity, and abundant functional groups (–SH, –NH₂), H-MnFe₂O₄-Cys exhibits excellent adsorption of heavy metal ions (Cr⁶⁺ and Pb²⁺ for instance) from wastewater. The high absorption efficiency and low manufacturing costs, coupled with the advantages of fast removal and magnetic recycling capability, make H-MnFe₂O₄-Cys a potential adsorbent for heavy metal ion contaminated water.