Study On Degradation Of Organic Pollutants By Perovskite Activated Peracetic Acid

With the increasing availability of pharmaceuticals and personal care products（PPCPs）on the markets,organic pharmaceutical products have generated a lot of waste and emissions.As an emerging organic pollutant,the removal rate of PPCPs in the traditional treatment process of the sewage plant is difficult to reach the standard.The advanced oxidation technology can efficiently remove such refractory organic pollutants in water,opening up new ideas for such wastewater treatment.Perovskite has a stable crystal structure,high catalytic redox activity,and can continuously improve its activation performance for certain oxidants through doping modification of A/B sites.It is a heterogeneous solid catalyst with bright application prospects.Peracetic acid（PAA）is a strong oxidant with excellent sterilization and disinfection properties.It is non-toxic,harmless and economical.It has been widely used in food processing and various wastewater treatment in the past 30 years.However,PAA is currently heterogeneous.There are not too many reports on the activation and reaction mechanism.In this study,perovskite was used to activate PAA to degrade a variety of organic pollutants in water.The perovskite La MO₃（M=Co,Ru,Fe,Mn,Ni,V）with different B-site metal elements and the perovskite LaCoRuCuO₃ doped with various B-site metal elements were synthesized by the sol-gel method to explore different perovskites Catalytic activation performance of ore.In order to make a more intuitive comparison,we used different perovskite activated PAA and pollutants to carry out a cross-crossing experiment,using a typical non-steroidal anti-inflammatory drug diclofenac sodium（DCF）as the target pollutant for the system study,and testing the effects of different control conditions on the degradation of DCF by perovskite-activated PAA were tested.Through a series of characterization tests,the structure composition of the perovskite were studied,including SEM,TEM,XRD and XPS analysis.The results show that the morphology of La MO₃ perovskite synthesized with different B-site metal elements is quite different;after the La Co O₃ perovskite is doped with Ru and Cu,the synthesized LaCoRuCuO₃ perovskite changes from a honeycomb shape to a three-dimensional oblate.Shape,but still has the basic crystal form of perovskite.In the La MO₃/PAA system,La Co O₃ and La Ru O₃ show excellent activation performance and can efficiently degrade a variety of organic pollutants.Through the dosage experiment,the proper dosage of perovskite is 50 mg·L^-1,and the dosage of PAA is 30 mg·L^-1.The main active species in the reaction were also identified through free radical quenching experiments.The results of quenching experiments and EPR test showed that it is not·OH but CH₃COO·and CH₃COOO·that play the main role in the system.In the LaCoRuCuO₃/PAA system,when the dosage of perovskite is 20 mg·L^-1,DCF can be effectively degraded,and the dosage of PAA is controlled to be 30 mg·L^-1 unchanged,and DCF can be used within 45 min under the condition of p H 7.It is completely degraded,and the degradation efficiency is greatly improved compared with the La MO₃/PAA system.On this basis,the effect of different reaction conditions on the degradation efficiency of DCF was investigated,and it was found that the degradation efficiency of DCF slowed down with the increase of Cl^-and HA concentration,and the degradation efficiency was the highest at the initial p H 9 of the reaction.In the material reusability experiment,LaCoRuCuO₃ showed good reusability,and the removal rate of DCF can still reach 98%in the fourth reusability.The metal ion permeability in the solution after the reaction was measured by ICP-MS,and it was found that the percolation amount of the LaCoRuCuO₃ perovskite was very low.The Co ion concentration in the solution was 1.19μg·L^-1,and the Ru ion concentration was 3.92μg·L^-1.The Cu ion concentration is 2.75μg·L^-1,indicating that the catalytic reaction mainly depends on the activation performance of the material.Free radical quenching experiment and EPR test results showed that CH₃C（=O）O·and CH₃C（=O）OO·play the main role in the system,which is consistent with the experimental conclusions of the La MO₃/PAA system.In addition,the products analysis of the DCF degradation reaction was carried out.A total of three intermediate products were detected in the LaCoRuCuO₃/PAA system.Based on these three degradation products,three main degradation pathways of DCF were proposed:C—N bond cleavage,decarboxylation and formylation.Finally,the degradation effect of the LaCoRuCuO₃/PAA system on a variety of organic pollutants was investigated.The results show that the system can efficiently degrade a variety of organic pollutants.However,since the reaction is not dominated by·OH,the removal effect of drugs（such as ibuprofen）specific to·OH is general,and it has a universal and efficient removal effect on other organic matter.This study proposes that the use of doped modified LaCoRuCuO₃ perovskite to catalytically activate PAA greatly improves the degradation efficiency of advanced oxidation,and this system has universality in the removal of most refractory organic pollutants in water.The research results have enriched the mechanism of perovskite used in catalysis and PAA advanced oxidation,and have made a great contribution to improving the efficiency of the existing perovskite/peroxidant system to degrade organic pollutants,and also provide new ideas and theories for water environmental pollution control.