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Fe3o4-ce@bc Activated Persulfate Oxidation Of Polycyclic Aromatic Hydrocarbons In Contaminated Soil

Posted on:2022-04-15Degree:MasterType:Thesis
Country:ChinaCandidate:Y WangFull Text:PDF
GTID:2491306602477634Subject:Environmental Engineering
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There are currently a large number of polycyclic aromatic hydrocarbons(PAHs)contaminated sites in China.Due to the "three causes" characteristics of PAHs,the concentration of PAHs in contaminated plots must be restored to below the control value before redevelopment and utilization can be considered.Persulfate advanced oxidation technology has been extensively studied in recent years due to its high selectivity,rapid efficiency,and low cost for aromatic compounds.However,persulfate requires activation to improve its oxidability.Traditional activation methods such as transition metal ion activation and metal oxide activation have the problems of easy quenching,poor effect and serious metal leaching.Therefore,in this study,Fe3O4-Ce@BC composite material was synthesized by hydrothermal-coprecipitation method to activate persulfate,which can efficiently remove PAHs in contaminated soil,and study its activation mechanism and remediation effect.First of all,taking the Fe3O4-Ce@BC composite material activated persulfate as the goal to degrade PAHs in the soil,the study determined the optimal synthesis conditions of the Fe3O4-Ce@BC composite material,including biochar pyrolysis temperature,cerium content,iron Content and so on.The Fe3O4-Ce@BC composite material was synthesized and analyzed by SEM,XRD,XPS,and FTIR.It can be seen that Fe3O4,CeCO3OH and CeO2 were successfully loaded onto the surface of biochar.Secondly,the influencing factors of Fe3O4-Ce@BC activated sodium persulfate to degrade the PAHs in the soil were explored.The effects of oxidant dosage,activator dosage,pH,water-soil ratio,time and other factors on the remediation effect of PAHs contaminated soil were explored.When the PS concentration is 0.5mmol/g,the dosage of Fe3O4-Ce@BC is 40mg/g,the water-soil ratio is 5:1,the initial pH=5,and the reaction time is 48h,remediation effect is the best.At this time,the total PAHs removal rate reaches 89.34%,the degradation rates of Nap,Phe,Pyr and BaP were 83.58%,74.28%,95.97%and 99.19%,respectively.At the same time,the dosing methods of the oxidizer and the activator are explored,and when the activator is dosed twice,and the oxidant is dosed once for the best effect.Finally,the mechanism of Fe3O4-Ce@BC activation of sodium persulfate is explored.In this study,EPR and free radical masking experiments were used to identify free radical species.EPR,and the properties of the materials before and after the reaction are analyzed through XRD,XPS,FTIR,Roman and other characterization methods.The possible reactions and reaction sites are summarized according to the free radical pathway and the non-radical pathway,SO4·-/·OH/O2·-/1O2 and the electron transport process dominate the degradation of PAHs in the system.The changes in the properties of the soil after the restoration and the remediation effect are studied,and the toxicity of the soil after the remediation is lower than that of the contaminated soil.
Keywords/Search Tags:soil remediation, polycyclic aromatic hydrocarbons, sodium persulfate, biochar, mechanism research
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