Efficient removal of pyrene by biochar supported iron oxide in heterogeneous Fenton-like reaction via radicals and high-valent iron-oxo species

Abstract

Biochar supported different doses of ferro ferric oxide (Fe3O4/BC) was synthesized with different pyrolytic temperatures and compared in catalyze oxidation of pyrene as a typical polycyclic aromatic hydrocarbon through heterogeneous Fenton-like reaction. The results illustrated that the 99.5% of pyrene in aqueous solutions was removed at the initial pH of 7.5 by the synthesized Fe3O4/BC5 with composite mass ratio of 1:5 without pyrolysis after 720 min reaction. The high catalytic efficiency was probably ascribed to the catalyzed oxidation of hydroxyl radicals and high-valent iron-oxo species which was confirmed by the changes of functional groups on Fe3O4/BC5 surface, electron paramagnetic resonance, dimethyl sulfoxide as a probe compound experiment and radical quenching experiment. Furthermore, the accelerated electron transfer of pyrene catalyzed degradation in Fe3O4/BC5/H2O2 system was measured by linear sweep voltammetry and electrochemical impedance spectroscopy. Six degradation products were identified by GC–MS, then the radical and electron transfer oxidation pathways of pyrene were proposed.