Study On Mechanism And Performance Of Novel Fe-based Z-scheme Photocatalyst

The rapid development of human society has produced a lot of pollution to the environment.Among these pollutants,endocrine disruptors and antibiotics are difficult to degraded by nature,they threaten the ecological environment and human health.Therefore,this paper selects the typical endocrine disruptors Bisphenol A?BPA?and antibiotic tetracycline?TC?as the pollutants,and study the effective removal method of them.Photocatalytic degradation has become a research hotspot due to its easy manipulation and environmental friendliness.Among the photocatalysts,nano?-Fe₂O₃ and polymer photocatalyst poly3-hexylthiophene?P3HT?have important research and application significance in photocatalysis due to their advantages.However,the defects of single-system photocatalysts limits the further improvement of their efficiency.Among these modification methods,Z-scheme structure not only promote the separation effect of photogenerated carriers,but also improve the redox performance of photocatalysts.Z-scheme photocatalysts are often constructed by precious metal or heavy metal semiconductors as materials,but these methods limit the application of Z-scheme in the environmental remediation.To improve the photocatalytic activity of?-Fe₂O₃,solve the problems of traditional Z-scheme,and provide a new material with high application potential for water remediation,this study proposed new strategies to construct Z-scheme material,and provides a new synthetic idea for the Z-scheme system.The synthesized material exhibited excellent pollutant removal effect,and the discussion of their mechanism deepens the understanding of the Z-scheme system.Besides,a novel immobilized Z-scheme nanoarray was synthesd.Based on the nanoarry,a photocatalytic reactor was designed,which improved the application value of Z-scheme system.The main experiments and conclusions of this study are as follows:?1?Polyoxometalate O-Ti-O was employed as the charge transfer mediator to connected?-Fe₂O₃ and P3HT?PTF?.XRD,BET,XPS,FT-IR,SEM-EDS,TEM and other methods were employed to characterized the structure and photo-energy utilization effect of PTF.The degradation effect was tested BPA as the target pollutant.As EPR and VBXPS results illustrated,the charge transfer mechanism of the PTF conforms to the Z-scheme mechanism.The theoretical calculation and XPS results proved that O-Ti-O constructed the Z-scheme charge transfer path through the Ti⁴⁺/Ti³⁺changing effect.The degradation rate of BPA in PTF can reach 99%in 60 minutes.The BPA degradation path in this system was analyzed through LC-MS and theoretical calculations.The Z-scheme structure improved the recovery ability of PTF.?2?Z-scheme structure was constructed between?-Fe₂O₃ and P3HT by using polyoxopolymer Al cluster as mediator?P/AC@F?.The structures and photo-electric efficiency were investigated by several methods The BPA and TC degradation effect of P/AC@F was also tested.The EPR and VBXPS results proved that the charge transfer mechanism of P/AC@F conforms to Z-scheme mechanism.The UPS results exhibited that AC constructed the Z-scheme system through the effect of built-in electric field.The degradation rate of BPA by P/AC@F can reach 98%in 60 minutes,and the degradation rate of TC can reach 96%in 70 minutes.The degradation pathway of BPA and TC were analyzed.P/AC@F can effectively degrade pollutants under different water quality conditions.?3?Z-scheme nanoarray?F1P?was synthesized by electrophoretic deposition.The structure and photo-energy utilization effect of F1P were characterized by several methods.BPA and TC were used as target pollutants to test the purification performance.The formation mechanism of the Z-scheme structure in F1P was discussed through theoretical calculation and XPS characterization results.The degradation rate of BPA in F1P can reach 99%in 75 minutes,and the degradation rate of TC can reach 97%in90 minutes.F1P showed a certain resistance to water quality changes.The degradation pathways of BPA and TC in F1P system were analyzed by LC-MS and theoretical calculations.This immobilized material exhibited good recycling performance.?4?The photocatalytic reactor was designed based on the immobilized nanoarray.The optimal dosage of the nanoarray was 240 cm²/L,and the optimal hydraulic retention time?HRT?was 10 hours.At this condition,the removal rate of TC can reach90%.Research on the kinetics of TC removal effect has proved that the degradation efficiency of pollutants can be improved by extending the HRT,when the concentration of influent pollutants is increased.Due to the strong redox ability of Z-scheme nanoarray,the competitive interference caused by humus can be resisted by reactor.The COD_Cr removal rate of simulated sewage No.1 can reach 40.11%,and the COD_Cr value of effluent water is 8.82 mg/L.The COD_Cr removal rate of simulated sewage No.2reaches 25.59%,and the COD_Cr value is 45.94 mg/L.The nano-composite array photocatalytic reactor exhibited stable operation effect and has certain application prospects in environmental remediation.