Improving The Fenton Catalytic Performance Of FeOCl Via Accelerating The Fe²⁺ Generation By Visible Light Or MoS₂

Wastewater pollution has been a serious problem owning to the great harmful influence on environment and human health.Organic pollutants in industrial wastewater are noticeable because of their toxicity,variety,and difficulty in degradation.Compared with traditional biological wastewater treatment,Fenton-like reaction of advanced oxidation process is preferable due to its high efficiency,fast degradation,and versatility.Heterogeneous iron oxychloride(FeOCl),which endows high activity and mild working conditions,has drawn much attention.However,the potential application of FeOCl is significantly hindered by the sluggish reduction kinetics of Fe3+ to active Fe2+.In view of the above shortcomings,we report the introduction of visible light,as well as the incorporation of Fe-O-Mo electron mediator into FeOCl via forming a FeOCl/MoS2 composite.Deep mechanism of enhancing FeOCl activity is explored.Inspired by the photosensitivity properties of FeOCl,we use photocatalysis coupling peroxymonosulfate(PMS)activation for effective BPA decontamination,thus Fe3+ can be rapidly reduced to active Fe2+.The as-prepared FeOCl exhibits good response to visible light and has a broad absorption spectrum.The reaction mechanism of FeOCl/PMS/Vis system is studied deeply.PMS is activated to generate active radicals by Fe2+ of FeOCl for BPA degradation.Then the asformed Fe3+ is reduced to Fe2+via trapping photoexcited electrons in conduction band(CB)of FeOCl,which effectively inhibites the recombination of photo-generated charges and the pollutants oxidation would recur via facilitating the Fe2+/Fe3+ redox recycle.The best performance of FeOCl/PMS/Vis system is～100%BPA(50 mg L-1)degradation efciency which achieves in 20 min.The FeOCl/PMS/Vis system also presentes impressive degradation performance at a wide pH range(pH=3-11)and shows well excellent stability and reusability.For accelerating the active Fe2+ regeneration,we report that the incorporation of electron mediator into FeOCl via forming a FeOCl/MoS2 composite can facilitate the Fe2+regeneration,thus leading to a significantly improved catalytic performance on methylene blue(MB)degradation.Fe-O-Mo acts as mediator via transferring electrons from Mo4+to Fe3+,thus the optimum Fe2+can always be kept for H2O2 activation,which leading to a satisfactory performance constantly.As a result,the removal efficiency of MB(50 mg L-1)achieves～100%within 2 mins with low dosage of FeOCl/MoS2(0.2 g L-1)and H2O2(0.6 mM).FeOCl/MoS2 Fenton-like system is favorable due to its broad working pH range(pH=3-9),high salinity tolerance(100 mM)and remarkable versatility.In conclusion,this study successfully promotes catalytic activity of FeOCl via introducing visible light or electron transfer mediator,and further reveals the special regeneration mechanism of Fe2+.For the first time,the activity and mechanism of FeOCl activating PMS under visible light are explored.This work highlights the promising way towards the high-performance Fenton-like iron-based catalyst.