NiFe₂O₄基催化剂的微波合成及其在微波场中光催化性能研究

【作者】 王莹；

【导师】 辛柏福；

【作者基本信息】 黑龙江大学 ， 分析化学， 2021， 硕士

【摘要】 近年来,为解决染料污水问题,逐渐开展外场辅助光催化的研究。其中,微波辅助光催化有紫外-可见光和微波场的协同作用,可大大提高有机污染物的降解效率,因此更加备受关注。目前,寻找适合于微波辅助光催化体系的高效催化剂是该领域研究的重点。因此,本文构建了以磁性吸波材料NiFe₂O₄为主体的新型催化剂,以达到在微波辅助光催化体系中高效降解有机染料的目的。使用甘油辅助微波溶剂热法结合后续煅烧过程,制备了NiFe₂O₄纳米球。用XRD、FTIR、XPS、SEM、TEM和UV-vis DRS等分析手段对制备样品进行表征,并考察其在微波无极灯（MEDL）光催化体系对亚甲基蓝（MB）的降解性能。结果表明,30 mg/L MB的降解率在10 min可达到88.6%,TOC矿化率可达到55%。通过与NiFe₂O₄纳米颗粒和商用P25的催化性能对比对光催化机理进行探讨,发现大比表面积结构和微波能量的有效利用是NiFe₂O₄纳米球具有高效降解能力的原因。同时,循环降解实验证实了所制备的催化剂具有良好的可回收再利用性能。在证实了NiFe₂O₄适用于MEDL光催化体系基础上,采用微波法制备了BiOCl/NiFe₂O₄复合材料,制成了二维片层包覆三维球体的异质结构。采用一系列的检测对所制备的BiOCl/NiFe₂O₄复合催化剂进行表征分析,并研究了所制备的复合物在MEDL光催化体系中的光催化性能。通过调节2种材料的复合比例和控制微波合成的辐照时间,对复合物的制备条件进行优化。实验结果表明,20%BOC-NFO的比例在微波辐照30 min时,所制备的BiOCl/NiFe₂O₄复合材料具有最高的光催化活性,5 min的催化时间即可使Rh B（30 mg/L）降解86.1%。此外,还通过活性物种捕获实验,对降解过程中的活性物种和催化机理进行了初步的探讨。更多还原

【Abstract】 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.更多还原