| Organic wastewater produced by natural processes,industry,and household activities contains a large amount of organic pollutants,which has a significant negative impact on human health and the ecological environment.Therefore,finding effective methods to treat organic wastewater is the primary consideration today.At present,a variety of methods for treating organic wastewater have been developed,including biological methods,physical methods,and advanced oxidation methods.Among them,the new advanced oxidation method has broad application prospects in the treatment of organic wastewater due to its high efficiency,fast and thorough reaction rate,and simple operation.The key step of advanced oxidation technology is to seek efficient,stable and environmentally friendly catalysts.Trimanganese tetroxide(Mn3O4)has many characteristics of excellent catalysts,but its composite with graphite-phase carbon nitride(g-C3N4)has little research on its catalytic activity.In addition,the heterogeneous catalytic system has the disadvantages of low mass transfer efficiency,difficulty in separation and recovery,and membrane technology can effectively improve these drawbacks.Therefore,this article first synthesized the Mn3O4/g-C3N4 composite by a two-step method and used it as an activator of persulfate(PMS)to degrade organic pollutants in water;by X-ray powder diffraction(XRD),Fourier Transform Infrared Spectroscopy(FT-IR),Scanning Electron Microscopy(SEM)and Energy Dispersive Spectroscopy(EDS),X-ray Photoelectron Spectroscopy(XPS)and other characterization techniques to analyze the surface characteristics of the catalyst,explore the effect of the amount of g-C3N4 added on the catalytic activity of Mn3O4 and the mechanism of the composite catalyst to activate PMS;Then select the composite catalyst with the best catalytic performance,load it with polytetrafluoroethylene(PTFE)membrane,construct Mn3O4/g-C3N4 catalytic membrane/PMS system,filter analysis of a variety of organic pollutants in water to evaluate the application potential of the catalytic membrane in activating PMS to degrade organic pollution.The contents are outlined:1.The Mn3O4/g-C3N4 composite was successfully synthesized by a two-step method,in which Mn3O4 nanodots(6-10 nm)were evenly distributed on g-C3N4 nanosheets.A Mn3O4/g-C3N4/PMS system was constructed to degrade tetrachlorophenol(4-CP)in water.The results show that the Mn3O4/g-C3N4 composite catalyst exhibits stronger catalytic capabilities than the single catalyst Mn3O4 and g-C3N4.In addition,the catalysts synthesized by adding different amounts of g-C3N4 nanosheets have different catalytic capabilities,and the Mn3O4/g-C3N4-150 catalyst showed the best catalytic ability.The effects of operating parameters such as catalyst dosage,pH,and PMS concentration on the catalytic degradation process were investigated in detail.The results show that the catalytic system is suitable for a wide pH range.Based on free radical quenching experiments and ESR spectrum testing,it was determined that the active species produced in the Mn3O4/g-C3N4/PMS system was mainly singlet oxygen(1O2)5 and a reasonable catalytic mechanism was proposed for the reaction system.2.In order to make the heterogeneous catalyst Mn3O4/g-C3N4 easy to separate and recover,and improve the mass transfer rate,we constructed a Mn3O4/g-C3N4 catalytic membrane(Mn3O4/g-C3N4@PTFE)by a simple vacuum filtration method.In the presence of PMS,the catalytic membrane has a high filtration and degradation effect on different organic pollutants tetrachlorophenol(4-CP),bisphenol A(BPA),rhodamine B(Rh B),levofloxacin.The stability of the membrane is measured by testing the reusability of the catalytic system,Mn ion elution,and changes in the surface membrane. |
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