Synthesis of magnetic CoFe2O4/ordered mesoporous carbon nanocomposites and application in Fenton-like oxidation of rhodamine B.

CoFe2O4/ordered mesoporous carbon (OMC) nanocomposites were synthesized and tested as heterogeneous peroxymonosulfate (PMS) activator for the removal of rhodamine B. Characterization confirmed that CoFe2O4 nanoparticles were tightly bonded to OMC, and the hybrid catalyst possessed high surface area, pore volume, and superparamagnetism. Oxidation experiments demonstrated that CoFe2O4/OMC nanocomposites displayed favorable catalytic activity in PMS solution and rhodamine B degradation could be well described by pseudo-first-order kinetic model. Sulfate radicals (SO4-·) were verified as the primary reactive species which was responsible for the decomposition of rhodamine B. The optimum loading ratio of CoFe2O4 and OMC was determined to be 5:1. Under optimum operational condition (catalyst dosage 0.05 g/L, PMS concentration 1.5 mM, pH 7.0, and 25 °C), CoFe2O4/OMC-activated peroxymonosulfate system could achieve almost complete decolorization of 100 mg/L rhodamine B within 60 min. The enhanced catalytic activity of CoFe2O4/OMC nanocomposites compared to that of CoFe2O4 nanoparticles could be attributable to the increased adsorption capacity and accelerated redox cycles between Co(III)/Co(II) and Fe(III)/Fe(II).

[Heterogeneous Activation of Peroxymonosulfate with Three-dimensional Ordered Mesoporous Co3O4 for the Degradation of Rhodamine B].

Three-dimensional ordered mesoporous Co3O4 was prepared by nanocasting method with porous silicon KIT-6 as the hard template and firstly used to activate peroxymonosulfate for the degradation of rhodamine B. The structural properties were characterized by BET, H-TEM, XRD, XPS, FT-IR. The results showed that three-dimensional ordered mesoporous Co3O4 presented far superior catalytic activity over conventional nanoscale Co3O4 due to its abundant space mesoporous channel structure and the large specific surface areas. Higher catalyst dosage and higher peroxymonosulfate concentration favored the decolorization of rhodamine B. The removal of rhodamine B could be accelerated in the presence of Cl- and H2PO4-; however, the decolorization of rhodamine B would be inhibited in the presence of NO3-, SO42- and HCO3-. Sulfate radicals were identified as the dominant active species for the decolorization of rhodamine B through radicals quenching experiments. Three-dimensional ordered mesoporous Co3O4 showed excellent catalytic activity even after five consecutive cycles.