Porous Fe2O3 microcubes derived from metal organic frameworks for efficient elimination of organic pollutants and heavy metal ions

Abstract

Increasing specific surface area and functional groups are two key ways to improve the adsorption performance of adsorbent materials. Herein, porous Fe2O3 (P-Fe2O3) microcubes composed of fine Fe2O3 nanoparticles (NPs) were facilely synthesized through the simultaneous oxidative decomposition of Prussian blue (PB) microcubes. Owing to their integrated features (i.e., large specific surface area of ∼155 m2 g−1 and large amount of Fe2O3 NPs), the synthesized P-Fe2O3 exhibited excellent adsorption capacities for heavy metal ions (175.5 mg g−1 for Cr(VI) and 97.8 mg g−1 for Pb(II)) and organic contaminants (159.4 mg g−1 for humic acid and 425.9 mg g−1 for methyl blue) from aqueous solutions. Based on the batch experiments, the adsorption isotherms could significantly conform to the Langmuir models. Combined with the microscopic analysis, the results suggested that the enrichment of Pb(II) on P-Fe2O3 was mainly attributed to the chemical binding between the electron donating oxygen ions of P-Fe2O3 surface and Pb(II), while the large available positive charge density could facilitate the effective adsorption of Cr(VI) due to ion exchange and electrostatic attraction. Furthermore, the surface complexation of organic pollutants on P-Fe2O3 was depended on the dipole moment and molar volume of the organic pollutant molecules. The consequences indicated that P-Fe2O3 could be served as a promising material for the decontamination of organic contaminants as well as the elimination of heavy metal ions from aqueous solutions. The findings presented herein played important roles in the purification of inorganic and organic contaminants on the available of inexpensive P-Fe2O3 NPs in natural environmental pollution cleanup applications.