Study On The Degradation Characteristics And Mechanism Of Emerging Pollutants In Fe-C₃N₄/rGo/PMS Coupled System

The deep treatment and reuse of wastewater is of great significance in enhancing the efficiency and effectiveness of water use and alleviating water scarcity.The development of efficient,low-consumption and environmentally friendly deep treatment technologies has become a research focus in the field of wastewater recycling.Advanced oxidation technology can efficiently remove toxic and harmful hard-to-degrade organic substances,or even completely mineralize them into CO₂ and H₂O,which is a very prominent advantage in the deep treatment of wastewater.The development of green,efficient and stable catalysts is the focus and difficulty of the advanced oxidation process.This research is based on a new inorganic nonmetallic material,graphitic carbon nitride（g-C₃N₄）,which is modified by doping to optimize the activation performance of peroxymonosulfate（PMS）.Combining the catalyst characterization with the degradation characteristics,the mechanism of pollutant degradation in this catalytic system was proposed.The main studies and conclusions are as follows.In this study,a ternary composite catalyst Fe-C₃N₄/r GO was successfully synthesized from melamine,ferric chloride hexahydrate and graphene oxide（GO）,and a coupled Fe-C₃N₄/r GO/PMS catalytic system was constructed.The physicochemical properties of the composite catalyst and the interaction relationship among the components were characterized by electron microscopy,XRD,FT-IR and XPS.The influence of the preparation conditions on the catalytic efficiency of the composite and the degradation characteristics of the organic compounds in the coupled system were synthetically researched via bisphenol A degradation.The experimental results confirmed that Fe and r GO were successfully doped into the skeleton structure of g-C₃N₄,in which Fe was clustered on the surface of lamellar r GO and g-C₃N₄ in ionic form,and the three components were connected by Fe-N and Fe-O bonds,with strong coupling and hybridization effects.As an ideal PMS activator,the carbon-based material can efficiently activate PMS to degrade organic pollutants in the absence of light,and the optimum PMS activation performance is achieved at 20%Fe doping and 30%graphene dosage.Under the optimized conditions of 0.15 g/L catalyst,1 mmol/L PMS and p H=6,100 ml BPA was completely removed within 20 min and this excellent performance was maintained over a wide p H range of 3-11.Quenching experiments and electron paramagnetic resonance spectroscopy showed that the Fe-C₃N₄/r GO/PMS coupled system produced a variety of active oxide species,mainly ¹O₂,with the coexistence of·OH、·SO₄^-and·O₂^-.The Fe（III）and C=O groups on the catalyst surface jointly participate in the activation of PMS,and the target pollutant bisphenol A was catalytically degraded by both the free radical pathway and the non-radical pathway.In addition,the influence of the actual water environment factors on the catalytic efficiency was investigated,and it was confirmed that the Fe-C₃N₄/r GO/PMS coupled system has good anti-interference ability,and the degradation efficiency of BPA can be maintained stably above 98%.The cycling experiments and the degradation experiments of different pollutants showed that the composite catalyst is stable and reproducible,and it can degrade and mineralize a variety of representative pollutants without selectivity,which has strong practical application capability.