Zinc/Iron mixed-metal MOF-74 derived magnetic carbon nanorods for the enhanced removal of organic pollutants from water

The preparation of magnetic porous carbon from a mixed-metal-organic framework by a two steps simple method is reported. By taking advantage that the calcination process at high temperature under inert atmosphere of zinc and iron MOFs results in the formation of carbons with excellent porosity and magnetic properties, respectively, MOF-74(Zn/Fe) prepared at room temperature was used as precursor for the synthesis of high porous magnetic carbons. The prepared materials were characterized by XRD, FTIR spectroscopy of adsorbed CO, SEM, TEM, N2 adsorption-desorption, Zeta potential analysis and energy dispersive X-ray spectroscopy. To check the potential as sorbent of the MOF-74(Zn/Fe)-derived magnetic porous carbon, adsorption isotherms of methylene blue and methyl orange were recorded and compared with those obtained using a non-magnetic MOF-74(Zn)-derived porous carbon. The maximum adsorption capacity for methylene blue and methyl orange was 370 and 239 mg g−1, which are higher than those reported for other magnetic adsorbents. The study of the extraction performance of the dyes at different pH, along with Zeta potential analysis, revealed that electrostatic and π-π interactions might be involved in the dyes removal. C-MOF-74(Zn/Fe) material showed good reusability with no apparent loss in dye extraction capacity after five cycles and the ability to treat large volume of dye polluted water. In addition, the developed C-MOF-74(Zn/Fe) showed excellent performance for the simultaneous removal of different endocrine disrupting phenols (bisphenol A, 4-tert-butylphenol and 4-tert-octylphenol) from water, demonstrating that mixed-metal-organic frameworks are promising precursors for the preparation of a wide number of new porous materials.