Microwave Synthesis Of NiFe₂O₄-based Catalysts And Their Photocatalytic Performance In Microwave Field

In recent years,in order to solve the problem of dye wastewater,external field coupled photocatalysis has been gradually studied.Among these,Microwave-assisted photocatalysis has the synergistic effect of ultraviolet-visible light and microwave field,which can greatly improve the degradation efficiency of organic pollutants and has attracted more attention.At present,searching for high-efficiency catalysts suitable for microwave-assisted photocatalytic systems is the focus of current research.Therefore,this paper constructed a new type of catalyst based on the magnetic material NiFe₂O₄ to achieve the purpose of effectively degrading organic dyes in a microwave-assisted photocatalytic system.NiFe₂O₄ nanospheres were synthesized using a glycerol-assisted microwave solvothermal process followed by an annealing method.The structural properties of NiFe₂O₄ were characterized using XRD,FTIR,XPS,SEM,TEM and UV-vis DRS,etc.And its degradation performance on methylene blue(MB)in the microwave electrodeless discharge lamp(MEDL)photocatalytic system was investigated.The results show that the degradation rate of 30 mg/L MB can reach 88.6%in 10 min,and the TOC mineralization rate can reach 55%.By comparing the catalytic performance of NiFe₂O₄ nanoparticles with commercial P25 to discuss the photocatalytic mechanism,it is found that the structure of large specific surface area and the effective utilization of microwave energy are the reasons for the high-efficiency degradation ability of NiFe₂O₄nanospheres.At the same time,the cyclic degradation experiment confirmed that the prepared catalyst has good recyclability and reuse performance.On the basis of confirming that NiFe₂O₄ is suitable for the MEDL photocatalytic system,the BiOCl/NiFe₂O₄ composite material was prepared by the microwave method.The structure of the composite is the heterostructure of two-dimensional BiOCl nanosheets grown on the surface of three-dimensional NiFe₂O₄ nanospheres.A series of test methods were used to characterize and analyze the prepared BiOCl/NiFe₂O₄composite catalyst,and the photocatalytic performance of the prepared composite was studied in the MEDL photocatalytic system.By adjusting the composite ratio of the two materials and controlling the irradiation time for microwave synthesis,the preparation conditions of the composite were optimized.The experimental results show that the BiOCl/NiFe₂O₄ composite prepared has the highest photocatalytic activity at the ratio of20%BOC-NFO under microwave irradiation for 30 min,and it could degrade 86.1%of Rh B(30 mg/L)in 5 min.In addition,by adding trapping agent in the process of photocatalysis,the active species and catalytic mechanism in the degradation process were preliminarily discussed.