Efficacy And Mechanism Of Bisphenol A Degradation By Cuprous Oxide Based Catalysts/Peroxymonosulfate System

The rapid development of economic society and industrialization has exacerbated the problem of environmental pollution,more and more emerging refractory organic pollutants have been discharged into environmental water bodies.As a typical endocrine disruptor,bisphenol A,which has been widely used in industrial production and daily life,is considered to be harmful to the ecological environment and human health.Therefore,there is an urgent need for researchers to develop corresponding treatment technologies to achieve efficient removal of bisphenol A.Advanced oxidation processes based on persulfates have received increasing attention in the field of water treatment due to its strong oxidizing ability,wide adaptability and low cost.The O-O bond of persulfate（PMS or PDS）molecules can be broken through a variety of activation methods to produce SO₄^·-for the oxidation of organic pollutants.With the development of persulfate-based advanced oxidation processes,novel non-radical oxidation pathways exhibit stronger substrate selectivity,higher oxidant utilization,and anti-background interference ability,which has become a new research hotspot.However,in the complex and diverse heterogeneous catalytic systems,the study of non-radical oxidation mechanism is still controversial,which restricts the further application of heterogeneous persulfate catalytic oxidation process in water and wastewater treatment.In this paper,on the basis of related research,a heterogeneous catalyst based on cuprous oxide（Cu₂O）was prepared to activate PMS for the degradation of bisphenol A.By controlling the synthesis conditions,cubic（c-Cu₂O）,octahedral（o-Cu₂O）and rhombic dodecahedron（r-Cu₂O）were prepared for investigating the effect of crystal structure on the catalytic activity.The results show that the catalytic activity is in the order of c-Cu₂O>o-Cu₂O>r-Cu₂O,and it’s related to the content of Cu 2p and oxygen vacancies on catalyst surface.The effects of reaction conditions and coexisting anions on the oxidation capacity of the c-Cu₂O/PMS were investigated,it exhibits strong adaptability and stable oxidation capacity.The results of radical quenching,radical trapping,solvent replacement and organic substrate selectivity experiments jointly revealed the non-radical oxidation mechanism in the process of c-Cu₂O-activated PMS for bisphenol A degradation.In situ FT-IR and Raman spectra further confirmed that the PMS molecules are activated on c-Cu₂O through outer-sphere interaction,leading to formation of reactive complex with stronger oxidation capacity,which can directly abstract electrons from bisphenol A molecules to achieve rapid oxidation of the target organics.To improve the removal efficiency of bisphenol A,we used nano-barium titanate particles with unique electronic structure and physicochemical properties to prepare BTO@Cu₂O composites by in-situ loading.The effects of Cu₂O morphology and BTO loading on the catalytic activity and bisphenol A degradation rate of BTO@Cu₂O were investigated,and it was found that the cubic BTO₆@c-Cu₂O could completely remove BPA（10 mg/L）within 60 minutes when the Ba Ti O₃ loading was6 mg.The characterization results show that the supported Ba Ti O₃ can regulate the electronic structure at the interface of the composite material and accelerate the electron transfer on the surface of Cu₂O,thereby enhancing its catalytic performance.The adaptability of BTO₆@c-Cu₂O under different parameters and in the presence of coexisting anions,natural organic matter was explored.The system has strong stability and can still achieve effective removal of bisphenol A.The main reactive species in the reaction system were identified,and the contribution of free radicals and singlet oxygen were excluded.The electron transfer routes between BTO₆@c-Cu₂O,PMS and bisphenol A was verified by electrochemical analysis,and the non-radical oxidation pathway was further described as formation of BTO₆@c-Cu₂O-PMS*reactive complex on the catalyst surface by activated PMS molecules,and directly abstracts electrons from BPA molecules for efficient removal of organic substrates.To further improve the activity of Cu₂O heterogeneous catalysis,in this work,transition metal ions-doped M-Cu₂O was prepared by element doping.And it was found that among Mn,Fe,Co and Ni doped Cu₂O,Fe-Cu₂O showed the highest catalytic activity,and the optimal doping amount of 1.0%could achieve 100%removal of bisphenol A（10 mg/L）within 30 mins.The characterization and theoretical calculation results show that Fe³⁺doping effectively modulates the microstructure and surface electronic state of Cu₂O,and enhances the interaction between active sites on catalyst surface and PMS molecules.Radical quenching and electron paramagnetic resonance techniques confirmed the existence of trace free radicals(SO₄^·-,^·OH and O₂^·-)in the reaction system,while the degradation of BPA still mainly relies on non-radical oxidation pathway,which shares the same mechanism with PMS activation by Cu₂O,forming surface-confined reactive complex（Fe-Cu₂O-PMS*）through outer-sphere interactions,and exhibits strong oxidizing ability to directly oxidize organic substrates via electron transfer.In this paper,the efficiency and mechanism of bisphenol A removal by PMS activation on Cu₂O-based catalysts were thoroughly studied,and the catalytic activity of the composites was effectively improved by means of in-situ loading and element doping.More importantly,the identification and analysis methods for the reactive species in the heterogeneous activated persulfate system were improved,and the non-radical oxidation mechanism based on the Cu₂O-activated PMS process was elucidated.