Degradation Of Bisphenol A By Persulfate Activated By Mineral Supported CuO/MgO Nanosheets

Bisphenol A（BPA）is a typical endocrine disruptor.Efficient removal of BPA from water is an urgent need to ensure water ecological security and human health.Advanced persulfate oxidation technology（SR-AOP_S）based on reactive oxygen species(SO₄^·-,OH^·and ¹O₂)has the advantages of strong oxidation capacity and wide p H range,which is a potential treatment technology for refractory organic compounds.Among them,peroxydisulfate（PDS）is an important research direction in SR-AOP_S due to its good stability and economy.Transition metal oxides（Such as CuO,Co₃O₄,etc.）can activate PDS through the redox cycle of metal ions,without additional energy input and mild reaction conditions,which has attracted extensive attention in the treatment of refractory organic compounds,However,there are still problems such as poor electrical conductivity and low electron transfer efficiency.Constructing oxygen defects on the surface of transition metal oxides can significantly improve the electron transfer efficiency and enhance the adsorption of PDS on the oxide surface,thus greatly improving the activation of PDS and degradation of pollutant.In this study,the composite of CuO and non-reducing alkali metal oxide MgO was constructed to adjust the surface charge distribution of CuO by utilizing the defect rich characteristics of MgO,and to enhance its activation performance of PDS to efficiently remove BPA from water.The main research contents and achievements are as follows:（1）CuO/MgO composite catalyst supported on Si O₂ surface was prepared by thermal transformation of metal-polyphenol complex（Cu-Mg-TA）on Si O₂surface.The optimized calcination temperature and CuO/MgO ratio is 600℃and 3/7 respectively.The morphology and composition of CuO/MgO composite catalyst on Si O₂ surface were analyzed by scanning electron microscopy（SEM）and transmission electron microscopy（TEM）.Combined with electron paramagnetic resonance spectroscopy（EPR）,X-ray photoelectron spectroscopy（XPS）and Raman,the surface oxygen defects of the composite catalyst and the effect of MgO on the surface charge of CuO were investigated.The results show that the CuO/MgO composite catalyst has a sheet structure,and the CuO nanoparticles with particle size of about 2 nm are evenly dispersed on the surface of the sheet MgO.The surface of the composite catalyst is rich in oxygen defects,and the active copper exists in the form of Cu³⁺with high redox potential.（2）The performance and influencing factors of activated PDS for BPA degradation by CuO/MgO composite catalyst were studied,and its selective oxidation capacity was investigated.The results showed that CuO/MgO composite catalyst could effectively activate PDS and remove BPA.Under the conditions of CuO/MgO and PDS concentration of 0.18 g/L and 0.2 m M,respectively,BPA（10 mg/L）could be completely removed within 50 min with a degradation rate constant of 0.09 min^-1,and the PDS utilization rate is high（△BPA/△PDS=37.3%）.The CuO/MgO/PDS catalytic system can efficiently degrade BPA in the p H range from 3 to 11,and is almost free from the interference of Cl^-and NO₃^-.In addition,Studies on the degradation of various organic pollutants have shown that CuO/MgO/PDS system had some selectivity for electron-rich organic compounds.（3）The mechanism of oxidative degradation of BPA by CuO/MgO/PDS catalytic system was analyzed by chemical quenching experiment and EPR test.The results showed that no reactive oxygen species were generated in the catalytic system,and BPA was mainly removed by electron transfer mechanism.The electron transfer mechanism was confirmed by electron quenching experiment and in situ electrochemical analysis.ATR-FTIR and in-situ Raman analysis showed that during the activation of PDS by CuO/MgO,PDS adsorbed on the surface of CuO/MgO with the assistance of oxygen defects,forming the activated CuO/MgO-PDS complex,which extracted electrons from BPA and then oxidized them away.XPS analysis showed that the surface of-OH and oxygen defects and the high-valence State of Cu³⁺were the key to the adsorption and activation of PDS by CuO/MgO composite catalyst.