Carbon-encapsulated MnFe2O4 nanoparticles: effects of carbon on structure, magnetic properties and Cr(VI) removal efficiency

In this work, the influences of carbon on structure, magnetic properties and Cr(VI) absorption efficiency of carbon-encapsulated MnFe(2)O(4)nanoparticles (MFO/C NPs) are studied. SEM images indicate that the fabricated MnFe(2)O(4)nanoparticles (MFO NPs) are enveloped by carbon layers, forming encapsulating structure. By the BET analysis, it is demonstrated that the average specific surface area of MFO/C samples is higher than that MFO sample. From FTIR and XPS spectra, the presence of carbon-coated MnFe(2)O(4)nanoparticles is confirmed. It is found that the Cr(VI) absorption efficiency of the MFO/C NPs first increases to reach the maximum value at 5% C concentration, and then decreases with the further increment of C concentration. The maximum absorption efficiency and capacity of 90.1% and 73.26 mg/g are obtained, respectively. Finally, a removal mechanism for the removal of Cr(VI) is proposed. The obtained results demonstrate that the carbon-encapsulated MnFe(2)O(4)NPs is a promising candidate as an advanced absorbent for the removal of Cr(VI) from wastewater.