Preparation of Fe-MOFs by microwave-assisted ball milling for reducing Cr(vi) in wastewater.

Fe-Based metal-organic frameworks (Fe-MOFs) were prepared with trimesic acid and FeSO4·7H2O via a microwave-assisted ball milling approach. The structure and thermal stability of the as-prepared Fe-MOFs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). When used to degrade 20 mg L-1 hexavalent chromium in aqueous solution, the Fe-MOFs were found to completely reduce a 100 mL solution within 120 min under natural light and a 400 mL solution within 90 min under Xe lamp irradiation. Under natural sunlight, 98% of the Cr(vi) was removed from a 40 mL solution after 40 min.