Copper Oxides/Carbon Nanocomposites For Persulfate Activation In Catalytic Degradation Of Methylparaben

Parabens,as typical preservatives,are frequently detected in environments due to the huge amount of use,and are classified as emerging pollutants of endocrine disruptors.Advanced oxidation processes?AOPs?based on persulfate have received comprehensively studies for organic pollutants remediation in recent years due to their distinct merits such as excellent oxidation capacity,high reaction selectivity,environmental friendliness,and wide range of adaptation.In this study,based on the review of the research status of activated persulfate oxidation technology to organic pollutants removal in the environment,the commonly used copper oxides as heterogeneous catalysts are easy to agglomerate,have insufficient active sites,and conduct electricity.With limited capacity and easy to cause secondary pollution,two copper oxide/carbon composite catalysts were prepared by two strategies of carbon material loading and metal-organic framework materials as precursors to activate persulfate to degrade methylparaben?Me P?.The structural characteristics of two copper oxide/carbon composites and the degradation kinetics of Me P degradation were systematically analyzed,the reaction mechanism of catalytic materials with different structures to activate persulfate were studied,and the structure-effect relationship between degradation reactions and materials were clarified.The research results could provide insight into persulfate activation by copper oxide/carbon composites for environmental organic pollution remediation.The main conclusions and innovations of this study are as follows:?1?The performance and mechanism of graphene-supported Cu Fe₂O₄ composites activated SPS for Me P degradation were proved.Graphene,as a good supporting material,could significantly improve the specific surface area and dispersibility of Cu Fe₂O₄.Appropriate amount of graphene can act as an electron shuttle and promote the circulation of active species in Cu Fe₂O₄,which effectively improve the utilization rate of active sites,leading to the high Me P degradation efficiency.EPR and quenching experiments show that Me P degradation is mediated by SO₄·^-and·OH radicals.DFT theoretical calculations confirmed that free radicals are more likely to attack carbon atoms with high negative charge density on the benzene ring,which further rationalizes the Me P degradation pathway.?2?The performance and structure-effect relationship between Me P degradation and Fe-doped Cu₂O/C hollow nanocomposites for PMS activation were clarified.Cu₂O/Fe/C prepared with MOFs as precursors can regulate Cu₂O into carbon shell-coated octahedral nanocrystals,effectively increasing the specific surface area and structural stability of Cu₂O.Appropriate Fe doping could accelerate the circulation of active species on the surface of the material,and significantly improve the efficiency of Cu₂O/Fe/C hollow nanoparticles to activate PMS for Me P degradation.The carbon shell structure in the composites can enhance the electron transfer rate and structural stability,and broadens its p H application range and resistance to ion levels in the environment.EPR and quenching experiments confirmed that Me P degradation is mainly achieved through singlet oxygen-mediated non-radical reaction pathways.