Magnetic CoFe2O4 nanocrystals derived from MIL-101 (Fe/Co) for peroxymonosulfate activation toward degradation of chloramphenicol

Abstract

In this study, porous magnetic CoFe2O4 nanocrystals (NCs) were successfully synthesized by using bimetal-organic framework (MOF) as a precursor, and used as catalysts to activate peroxymonosulfate (PMS) for the removal of chloramphenicol (CAP) in the solution. The structure and physicochemical properties of CoFe2O4 NCs were thoroughly examined by a series of characterization techniques. The results revealed as-synthesized CoFe2O4 had a nanorod-shaped structure with high specific surface area (83.00 m2 g−1) and pore volume (0.31 cm3 g−1). Furthermore, the degradation efficiency (100%) and the removal of total organic carbon (68.09%) were achieved after 120 min with 0.1 g/L CoFe2O4 NCs, 2 mM PMS and 10 mg/L CAP at pH of 8.20. In addition, effects of catalyst dosage, PMS dosage, initial pH values, CAP concentration and co-existing anions as well as natural organic matters in the solution on the degradation efficiencies were studied and all the removal can be well fitted with pseudo-first-order kinetic model (R2 > 0.96). Sulfate radicals (SO4•−) and hydroxyl radicals (HO•) were proved to be two main reactive species for CAP removal in CoFe2O4/PMS system based on quenching experiments. CAP was degraded by the main pathways of dichlorination, denitration, decarboxylation, hydroxylation, ring cleavage and chain cleavage on CoFe2O4/PMS system through high performance liquid chromatograph-mass spectrometry analysis. We believe that this study would be very meaningful to promote the applications of MOFs-derived catalysts on the SO4•− based advanced oxidation processes (SR-AOPs) for the environmental remediation.