Decolorization of Acid Orange II dye by peroxymonosulfate activated with magnetic Fe3O4@C/Co nanocomposites

New metallic cobalt loaded magnetic nanocomposites (Fe3O4@C/Co) were prepared by calcination and in situ reduction of the Co2+-impregnated magnetic carbon nanoparticles of Fe3O4@C at 900 degrees C under a nitrogen atmosphere. Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), vibrating sample magnetometry, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the properties of the composites and the loading of metallic Co-0 in the material was clarified. The catalytic properties of the nanocomposites Fe3O4@C/Co in activating peroxymonosulfate (PMS) for decolorization of Acid Orange II (AO II) dye in aqueous solution were investigated. Fe3O4@C/Co nanocomposites exhibited high activity in PMS activation for AO II decolorization. Complete decolorization of AO II solution could be achieved in 20 min within near neutral pH range (pH 6.4-8.5), while a complete decolorization occurred in 40 min for the as-prepared solution without pH adjustment (pH 4.05). The effects of several parameters including pH, catalyst load, PMS concentration and reaction temperature on the catalytic activity were also investigated. Sulfate free radicals activated from PMS were proposed to be the dominant active species in the Fe3O4@C/Co + PMS system for AO II decolorization. The catalytic and decolorization mechanism was suggested. The catalyst Fe3O4@C/Co could be recycled easily by a magnet with good reusability. This study provides a promising method for the activation of green oxidant, PMS, by the new magnetic nanocomposites for environmental remediation and oxidation catalysis.