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

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.