Study On Activated Persulfate By Bismuth-coated Copper-based MOF Materials To Degradation Active Black 5

Azo Dye wastewater was one of the common harmful industrial wastewater,which was characterized by high COD concentration,high chroma,complex and variable fractions.Hence it was difficult to effectively treat Azo Dye wastewater by conventional chemical oxidation method.Advanced oxidation technology（AOPs）based on persulfate（PS）had strong degradation ability and specific selection ability for refractory wastewater.It was of great significance to explore efficient persulfate activated materials for its application.In this paper,active black 5（RB5）was selected as the degradation object of Azo Dye wastewater,and bismuth coated copper base organic framework material（HKUST-1@Bi）was prepared by solvothermal method.By constructing HKUST-1@Bi/permonosulfate（PMS）system to degrade RB5,the performance and activation mechanism of HKUST-1@Bi activated permonosulfate were systematically investigated,and the following research results was obtained:（1）HKUST-1@Bi with core-shell structure was successfully prepared by solvothermal method.Using HKUST-1 material as the core,Bi coating was grown in situ,and HKUST-1@70%Bi formed a complete core-shell structure.EDX showed that HKUST-1@Bi contained Bi,Cu,C,O and other elements.XRD characterization found that sharp characteristic peaks appeared in the range of 2θ=5°-20°,which proved that the material had a good crystal form and exhibited a typical metal-organic framework（MOF）crystal structure.The material had good crystal shape,and Bi coating did not damage the internal structure of the crystal.BET characterization showed that the nitrogen adsorptions-desorption isotherms of the material changed from type I to type IV with the increase of Bi loading capacity,and the specific surface area of HKUST-1@70%Bi was 423.16 m²/g,Pore size was 7.67 nm.（2）HKUST-1@Bi/PMS system was established to degrade RB5.The catalytic performance of the material was improved by the loading of Bi,and HKUST-1@70%Bi had the best activation performance.RB5 degradation follows a quasi-second-order kinetic model with a constant of 0.002 L·mg^-1min^-1.When the material dosage was 0.7 g/L,the initial concentration of PMS was 0.7 mmol/L,and the concentration of RB5 was 100 mg/L,the RB5removal rate could reach 92.7%,and the mineralization rate reached 69.1%.The experimental results showed that both mechanical stirring and aeration can reduce the removal rate of RB5,and the reaction system had a strong ability to resist the fluctuation of pollutant concentration,and had a good treatment effect on a wide p H range（5-11）,The removal rate can be maintained at about 80%.（3）Radical quenching experiment found that the reaction produced sulfate radical（SO₄^-·）and hydroxyl radical（·OH）,SO₄^-·Occupy the main leading position.Phenol quencher can cut off the charge transfer channel between material surface and PMS.SO₄^-·and·OH characteristic peaks was detected by EPR.Uv-Vis spectra showed that the naphthalene ring structure and azo bond with RB5 were destroyed,resulting in formation of small intermediate organic matter.The mineralization rate of HKUST-1@Bi/PMS to RB5 can reach 69.1%.XPS demonstrated that Bi was coated on the surface of HKUST-1,which was Bi₂O₃ formed into Bi-O bonds.The activation depends on the Cu（I）/Cu（II）cycle.The Surface Bi coating enhances the electron transfer efficiency,and Bi/Cu forms the bimetallic active center,which plays a synergistic activation effect.After four cycles of use,the RB5 removal rate of the material is 77.9%,indicating that HKUST-1@Bi has reusable potential.