Study On Dye Removal By Dual Z-scheme MIL-88A（Fe）/Ag₃PO₄/AgI Photo-fenton Catalyst

Rhodamine B（Rh B）in dye wastewater has the characteristics of refractory degradation and easy accumulation,which poses a great threat to humans.Photo-Fenton technology has a good degradation effect on dyes,so it has become a research hotspot for processing dyes.MIL-88A（Fe）has high activity in the photo-Fenton system.However,the e^﹣-h^﹢pairs produced by MIL-88A（Fe）photoexcitation is easy to recombine,and the stability in water is insufficient,etc.These factors limits its application.Photocatalytic activity can be enhanced by constructing heterojunctions.Based on this,the dual Z-scheme MIL-88A（Fe）/Ag₃PO₄/AgI（MAI）ternary composite was prepared in this paper.Through various characterization methods,the morphology,structure,surface chemical composition,light absorption performance,and photoelectric performance of MAI were investigated.Meanwhile the Rh B removal mechanism of photo-Fenton was investigated.The main contents of this paper are as follows.1.Preparation and characterization of MIL-88A（Fe）/Ag₃PO₄/AgI photo-Fenton catalystsMIL-88A（Fe）was prepared by simply oil bath heating.MIL-88A（Fe）was used as the carrier,and MAI ternary composites were synthesized by in-situ precipitation method and ion exchange method.Rod-shaped MIL-88A（Fe）was used as a carrier to reduce the agglomeration of Ag₃PO₄ and AgI particle.The PL,EIS and i-t curves showed that MAI has high electron-hole pair separation efficiency,small charge transfer resistance,and high photocatalytic activity.2.Performance study on the degradation of Rh B by MIL-88A（Fe）/Ag₃PO₄/AgI photo-Fenton catalystSynthetic MAI was used for the exploration of photo-Fenton removal of Rh B.Under the best optimized condition of 0.5 g/L catalyst,initial p H 3.0,0.4 mmol/L H₂O₂,100 m L 20 mg/L Rh B,the material completely degraded Rh B within 20 min.The catalyst could be maintained high catalytic property after 5 cycles.The dual Z-scheme heterojunction formed by MAI reduced the recombination of electron-hole pairs and improved photocatalytic activity.In addition,free radical capture experiments and EPR showed that h^﹢,·O₂^﹣and·OH are the main active substances in the MAI/Vis/H₂O₂ catalytic system.Finally,a possible mechanism for the catalysis of MIL-88A（Fe）/Ag₃PO₄/AgI is proposed.