Study On Properties And Mechanism Of Bimetallic Activated Persulfate Degradation Of Polycyclic Aromatic Hydrocarbons

With the rapid development of industry,groundwater pollution is increasing,and pollution control of groundwater environment has become a global problem.Polycyclic aromatic hydrocarbon pollutants are one of the most common organic pollutants in groundwater pollution due to its complex composition,structural stability and half-life.Long,difficult to remove with traditional biological,physical and chemical methods.And most of the polycyclic aromatic hydrocarbon pollutants have certain toxicity and are easy to accumulate in the living body,resulting in cancer,teratogenicity and mutagenicity of humans and animals.Advanced oxidation technology based on sulfate radicals as a new chemical repair method can oxidize and remove pollutants in a short time,but persulfate needs to be activated to better degrade pollutants.Existing activated persulfate The methods have the problems of large energy consumption for repair,secondary pollution,and easy oxidation of the activator.Bimetal is a composite metal catalyst that connects active metals to less active metals?precious metals?by chemical or physical methods.It has the characteristics of preventing rapid corrosion and agglomeration of base metals and increasing the surface activity of base metals.The field of pollutant remediation has a good application prospect.The use of bimetallic activated persulfate to degrade polycyclic aromatic hydrocarbons has achieved rapid and efficient removal of polycyclic aromatic hydrocarbons,and further analysis of the products of polycyclic aromatic hydrocarbon degradation,further illustrating the degradation pathway of polycyclic aromatic hydrocarbons.In this paper,the Cu/Fe bimetallic material was prepared by displacement method,and the naphthalene solution was activated by using sodium persulfate as catalyst.The investigation was carried out:?1?optimization of preparation conditions of Cu/Fe;?2?structural characterization of Cu/Fe?3?Catalytic performance of Cu/Fe catalyst;?4?Influencing factors of Cu/Fe-catalyzed degradation of polycyclic aromatic hydrocarbons by sodium persulfate;?5?Analysis of intermediates of Cu/Fe-activated sodium persulfate to degrade naphthalene;The research indicates:?1?Cu/Fe catalyst was prepared by displacement method with zero-valent iron as base metal.The preparation conditions of Cu/Fe catalyst were optimized by mixing method,mixing time and copper loading rate.The results showed that Cu/The best mixing mode of Fe catalyst is ultrasonic mixing.The optimum mixing time is 20min.The theoretical catalytic loading rate of copper is 20%.?2?The Cu/Fe catalysts before and after the reaction were characterized by XRD and XRF.The analysis of XRD showed that the Cu/Fe catalyst consisted mainly of Fe and Cu,and the surface of the Cu/Fe catalyst after the reaction appeared.Copper oxide and iron hydroxide;XRF results show that the mass fraction of iron in the Cu/Fe catalyst is 71.9%,the mass fraction of copper is 27.6%,and also contains trace amounts of Mn and Mg.?3?Cu/Fe catalyst has a significant effect on the degradation of naphthalene by activated sodium persulfate.It has stronger catalytic performance than zero-valent metal.The catalytic degradation of naphthalene by different Cu/Fe dosages follows quasi-first-order reaction kinetics.Regularity;after repeated use of Cu/Fe catalyst three times,the degradation rate of naphthalene can still be maintained above 90%;?4?In the experiment of factors affecting the degradation of naphthalene by sodium persulfate activated by Cu/Fe,the pH value,Cu/Fe dosage,sodium persulfate dosage and initial concentration of naphthalene have certain effects on the degradation effect.When the pH of the solution is acidic?pH?5?,the dosage of Cu/Fe catalyst is 0.1g,and the dosage of sodium persulfate is 0.4g,the degradation rate of naphthalene reaches 98%;?5?The free radical trapping experiment of Cu/Fe-activated sodium persulfate to degrade naphthalene shows that the free radicals that oxidize in the reaction of Cu/Fe-activated sodium persulfate to degrade naphthalene are·OH and SO₄^-·,?6?GC-MS analysis of naphthalene degradation intermediates showed that the intermediates of naphthalene degradation were mainly open-ring aldehydes,phthalic acid derivatives and alkanes,and naphthalene under the interaction of·OH and SO₄^-·First,a benzene ring scission addition reaction is carried out to form a ring-opened aldehyde,which is then oxidized to a phthalic acid derivative and an alkane species,and finally all mineralized into carbon dioxide and water.