Construction Of Heterogenrous Photo-fenton System Based On MoS₂ Composites To Treat Environmental Wastewater

The Fenton reaction can degrade organic pollutants via the generation·OH radicals through the reaction of Fe（II）and H₂O₂.To enhance degradation,current research is mainly focused on the development of various catalysts to improve the generation of·OH radicals vis accelerate the cycle of Fe（II）/Fe（III）.MoS₂ has received increasing attention in the field of photoelectric catalysis due to its high abundance,low cost,high activity,high stability and unique photoelectric properties driven by its two-dimensional structure.In this paper,a heterogeneous photo-Fenton system was constructed to degrade dyes and antibiotics in wastewater based on different forms of MoS₂ composites.Experimental conditions were optimized,and the mechanisms during the catalytic process was explored.（1）The 2D MoS₂ nanosheets obtained by liquid phase exfoliation were doped into rod-shapedα-Fe OOH synthesized by hydrothermal method to prepare composite materials,and H₂O₂ was combined to construct a photo-Fenton system.The degradation efficiency ofα-Fe OOH/1wt.%MoS₂ for MB,Rh B and TC at a concentration of 20mg/L under simulated sunlight can reach 98.57%,84.24%and 80.47%in25 min.The doping of MoS₂ can broaden the light absorption range ofα-Fe OOH,generate more photogenerated electrons to participate the reaction.The exposed Mo（Ⅳ）on the surface of MoS₂ can promote the Fe（Ⅱ）/Fe（Ⅲ）cycle.Therefore,the synergistic effect of photocatalysis and Fenton catalysis ofα-Fe OOH/1wt.%MoS₂ promotes the oxidative degradation of pollutants.Experiments proved that the·OH and·O₂^-produced were involved in the degradation of pollutants.Repeated stability experiments showed that theα-Fe OOH/1wt.%MoS₂ composite has excellent stability.（2）Fe OOH（QDs）were loaded onto 3D flower-like MoS₂ to prepare and characterize the composites through hydrothermal and chemical deposition reactions.The heterogeneous photo-Fenton system of 1wt.%Fe OOH（QDs）/MoS₂+H₂O₂ was constructed to degrade MB and TC.The MB degradation rate reached 99.05%in 8 min,and the degradation rate of TC reached 91%in 30 min.Flower-like MoS₂ as a carrier has good stability and strong adsorption performance.Meanwhile,the conversion of Mo（Ⅳ）/Mo（Ⅵ）can promote the cycle of Fe（Ⅱ）and Fe（Ⅲ）to increase the decomposition rate of H₂O₂.Experiments with free radical traps showed that·OH and·O₂^-free radicals are mainly responsible for the oxidative degradation of pollutants.The 1wt.%Fe OOH（QDs）/MoS₂composite material has high stability and can be used cyclically.（3）MnO₂ nanoparticles and 3D flower-like MoS₂ composite materials were prepared by hydrothermal method,and combined with PMS to construct a Fenton-like system.Under simulated sunlight,the1wt.%MnO₂/MoS₂ composite catalyst can degrade 96.86%of TC in 40min,and the system has a wide working p H range（from 4.0 to 10.0）.The redox cycle of Mn（IV）/Mn（III）and Mo（IV）/Mo（VI）in the system synergistically activates PMS to generate active free radicals to degrade pollutants.Free radical capture experiments show that·OH and·SO₄^-participate in the oxidation process of TC.After five cycles,the 1wt.%MnO₂/MoS₂composite still has high catalytic activity.