The Study On The Degradation Of Bisphenol A Catalyzed By Fenton-like Reaction With Perovskite Oxide

Refractory pollutants such as endocrine disrupting chemicals（EDCs）have been detected in various kinds of water bodies with increasing human health concerns.Advanced oxidation technology such as Fenton-like reactions has become a hot research topic for the degradation of EDCs.Perovskite oxide has been widly sued in Fenton-like reactions due to its unique structure that defectscould be created and the valence state of elements are adjustable with element doping.In this paper,the mechanism of Fenton-like reaction was studied through substitution,doping and modification of perovskite oxide LaFeO₃ for the degradation of bisphenol A（BPA）.The main contents and conclusions are as follows:（1）The cubic LaCu_xFe_1-xO₃ catalyst was prepared by the citric acid complexation method.The sintering temperature of the catalyst was determined to be 700℃by thermogravimetry（TG）.Analysis of X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,scanning electron microscopy（SEM）and N₂ physical adsorption showed that copper was succeeded in replacing part of the iron into the LaFeO₃ lattice.The specific surface area decreased,however the crystal crystallinity and stability of the catalyst were enhanced as the increase of calcination temperature.The catalytic efficiency was enhanced by the substitution of Cu with the best performance achieved with LaCu_0.5Fe_0.5O₃（x=0.5）,and the reaction was in accordance with the pseudo first order kinetics.XPS analysis before and after the catalytic reaction showed that there was synergistic effect between Fe and Cu,and oxygen vacancy on the catalyst surface played an important role in catalysis.（2）Under dark condition the degradation of BPA by the system of LaCu_0.5Fe_0.5O₃+H₂O₂demonstrated a BPA degradation efficiency of 91.7%in 120 min and the TOC removal rate of 59%.The stability of the material was confimed with 5 sequential degradation experiments（pH=6.0,H₂O₂ concentration of 12 mmol/L,BPA concentration of 20 mg/L and the dosage of catalyst is 1.0 g/L）.The degradation ratio of BPA in Fenton-like system increased further to 99%and the removal rate of TOC was 68%under visible light irradiation.The active species quenching experiment and electron spin resonance（ESR）analysis showed that the main active species in the reaction was·OH.HPLC and gas phase mass spectrometry（GC-MS）analysis showed that·OH mainly attacked alkyl and hydroxyl groups and benzene ring to degrade BPA.（3）Ca doped La_1-xCa_xMO₃（M=0.5Fe/0.5Cu）were prepared by the citric acid complexation method.XRD and SEM analyses showed that doping did not change the crystal structure and morphology.The degradation of BPA by the system of La_1-xCa_xMO₃+H₂O₂ demonstrated that the catalytic performance of La_1-xCa_xMO₃ was better when x=0.05 than that of LaMO₃.The degradation rate of BPA and the removal rate of TOC was 98.2%and 62.0%.However,the stability of the material was reduced.ESR analyses again indicated that oxygen vacancy in the catalyst is an important driving force for the catalytic reaction.