Activation of peroxymonosulfate by metal–organic frameworks derived Co1+xFe2-xO4 for organic dyes degradation: A new insight into the synergy effect of Co and Fe

Abstract Metal–organic frameworks (MOFs) derived CoFe2O4 is regarded as a promising catalyst in pollutants control due to its good performance for peroxymonosulfate (PMS) activation. However, the study towards organic dyes degradation is rare and the mechanism of the synergy effect of Co and Fe is not clarified. Herein, the MOFs derived M-Co1+xFe2-xO4 with more Co(III) in octahedral sites was prepared and used to degrade organic dyes by activating PMS. Under optimized conditions, the Rhodamine B (RhB) degradation kinetics rate of M-Co1+xFe2-xO4 is 0.260 min-1, which is 20 times higher than the commercial Co3O4 (0.013 min-1). SO4•- plays the vital role in RhB degradation and the contribution of Co(III) in octahedral sites is greater than that of Fe for PMS activation. Under weak acidic condition (pH 5), the effect of surface adsorbed OH- on PMS activation is negligible meanwhile the valence conversion of Fe is absent, implying the mechanism of synergy effect of Co and Fe under such condition is different from what previously reported. This work would shed lights on understanding the origin of the activity of CoFe2O4 in PMS activation and developing PMS-based technologies for organic dyes wastewater treatment.