FeOOH@MoS2 as a Highly Effective and Stable Activator of Peroxymonosulfate-based Advanced Oxidation Processes for Pollutant Degradation

Abstract Fe-based materials are widely used as activators in advanced oxidation processes (AOPs) for the degradation of persistent organic pollutants because of their high activity and environmental friendliness. The continuous consumption of Fe2+ and the generation of excessive Fe3+, however, lead to the formation of sludge (iron cement) and the degradation of the performances of materials. In this work, we report MoS2 with a self-assembled ultrathin Fe (oxy)hydroxide layer on the surface (FeOOH@MoS2) as a highly effective and stable activator for peroxymonosulfate (PMS)-based AOPs system. The FeOOH@MoS2/PMS system performed exceptionally for removing antibiotics from aquatic environment under both acidic and basic conditions, with function pH condition from 4 to 10. The stability of FeOOH@MoS2 was also outstanding, with only 10.1% decrease after 5 cycles under pH 8, which is much better than conventional heterogeneous Fe-based activator for PMS based AOPs. The combination of quenching experiments, electron paramagnetic resonance (EPR) tests and surface analysis suggest that such high performance is attributed to high catalytic activity of MoS2 as the co-catalyst and the strong interface interaction between MoS2 and FeOOH. While the Fe2+FeOOH in FeOOH effectively activate PMS to produce SO4•− and •OH radical to remove antibiotics, the produced Fe3+FeOOH is reduced back to Fe2+FeOOH by MoS2 co-catalyst, enabling the recycle of Fe2+. Our results provide a facile strategy for improving the activity and stability of heterogeneous Fe-based catalysts for AOP systems, particularly under basic environment, which contribute towards the large-scale implementation.