The synthesis of hierarchical ZnFe2O4 architecture and their application for Cr(VI) adsorption removal from aqueous solution

• Bowknot-like precursor is obtained via poval-mediated precipitation reaction.
• The growth mechanism of the hierarchical structure has been discussed.
• Mesoporous ZnFe2O4 hierarchical superstructure has been successfully synthesized.
• The ZnFe2O4 superstructures have been applied to the removal of Cr(VI).

The bowknot-like ZnFe2O4 superstructures have been synthesized by the decomposition of the zinc ferrioxalate microstructures, which are prepared by facile method at room temperature. The obtained products are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and nitrogen sorption measurements. The adsorption performances of bowknot-like ZnFe2O4 superstructures are tested with the removal of typical pollutants of Cr(VI) from simulated wastewater. The results show that the as-prepared bowknot-like ZnFe2O4 superstructures can effectively remove Cr(VI) from the wastewater. Kinetics of the Cr(VI) removal is found to follow pseudosecond-order rate equation. The adsorption isotherms of bowknot-like ZnFe2O4 superstructures can be described very well by the Langmuir equation. Therefore, the as-obtained bowknot-like ZnFe2O4 superstructures are promising absorbents for wastewater treatment.

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