Mechanism Of Advanced Oxidation Processes Remediation For Trichloroethylene And Typical Antibiotics Contaminates In Groundwater

In recent years,the problem of organic pollution in groundwater is becoming more and more serious.More and more attention has been paid to the degradation of organic pollutants effectively in groundwater and it has become a hot topic in environmental geochemistry.It has great practical significance to treat pollutants properly and make them harmless to the environment.Currently,advanced oxidation technology based on sulfate radical has obvious advantages due to its wide application range of pH.This paper aims to solve the problem of groundwater pollution.Based on the common pollutants in groundwater,trichloroethylene(TCE)and new antibiotics pollutants(SAs and TCs)as the research object,using iron-based catalyst activate PMS to degrade these two kinds of organic pollutants,to identify the activation process,discussed the degradation mechanism and transformation pathways.It will provide a theoretical basis for the practical application.The BNF/PMS system was constructed to achieve the rapid and complete degradation of TCE under weak alkaline conditions.BNF showed much higher catalytic efficiency than that of common and single modified nZVI.Sulfate radical played a major role in the degradation of TCE by BNF/PMS.As a kind of porous and ideal supporting material,biochar was applied to the modification of nZVI,which inhibited the agglomeration of nZVI and greatly improved the activation efficiency.Fe/C/PMS system can efficiently degrade TCE,but the mechanism was different from BNF/PMS.The main role in the reaction was singlet oxygen and superoxide,which contributed to the oxygen functional groups on the biochar surface.For the degradation of sulfapyridine(SPY),it could be efficiently degraded under the three systems(PMS,BNF/PMS,Fe/C/PMS).PMS can degrade SPY through its own oxidation,but the amount was large;Activating PMS by BNF or Fe/C,the dosage of PMS could be reduced.Among BNF and Fe/C,Fe/C activated PMS had better degradation SPY effect.Different kinds of free radicals were produced in the three systems,but their degradation pathways were not different.For oxytetracycline(OTC)degradation,the three systems(PMS,BNF/PMS,Fe/C/PMS)can also achieve efficient degradation.PMS can be used alone to degrade OTC;Activated PMS by BNF or Fe/C,the amount of PMS could be reduced.Among BNF and Fe/C,BNF/PMS was more suit for OTC degradation.In terms of mechanism,PMS self-oxidation can easily lead OTC to hydroxylation.Sulfate radical generated by BNF/PMS can easily quinoninize of OTC.Fe/C/PMS is easy to decarbonylation with singlet oxygen.All three systems can degrade OTC into small non-toxic molecules finally.