Design Of Iron-based Magnetic Nanocomposites Catalysts And Their Catalytic Performance Research

Advanced oxidation technologies(AOPs)have attracted wide attention owing to their excellent performance in the degradation of complex and stubborn organic pollutants in the waste water.So far,AOPs have been evolved gradually from the initial Fenton reaction to the Fenton-like reaction as application demand.The reasonable design of the catalyst is the key step for the actual application and promotion of AOPs,but there are still many problems,such as the narrow p H range of application,the easy agglomeration of catalyst particles,the low efficiency of photoelectric transfer and the high cost of recycling.To solve aforementioned problems,in this research,novel magnetic nanocomposite catalysts based on monomer iron-based catalysts have been designed through magnetic junction,heterogeneous construction and dispersed by carrier.Therefore,the nanocomposite show excellent catalytic performances,which can be easily recycled by magnetism.The superior performances are original from the hetergenious couple on the microscopic scale.The major research contents about our research are summarized as follows:(1)The magnetic Fe₃O₄/?-Fe OOH nanocomposite catalyst have been synthesized using a single iron source via one-step hydrothermal methods.And the ratios of two phases in the nanocomposite can be well adjusted by changing the amount of reducing agent added.It has high specific surface area with rich mesopores.Compared to monomers,its visible light absorption performance and photoelectron transfer rate are improved significantly,and it can be separated magnetically and recycled after pollutant degradation due to the coupled magnetic Fe₃O₄particles.The composite catalyst shows excellent organic degradation capability.Under the condition of p H=7,99.9%tetracycline hydrochloride(TC)can be degraded within 90 min,and the degradation rate of TC is above 95%in the p H range from 5 to 9.The ultra-high TC degradation efficiency benefits from the significantly improved electron transfer efficiency of the composite catalyst,the adsorption between tetracycline hydrochloride and more critical superoxy radicals produced on the degradation of TC.The study of degradation process reveals that TC will decompose gradually into small molecules through the processes of deamination,demethylation and hydroxylation,and finally realize the path of mineralization.(2)Novel ternary magnetic nanocomposites of Fe₃O₄@Fe S₂/C have been prepared through the vulcanization process using the Fe@ZIF-8 as template.The catalyst with a high specific surface area contains abundant graphene defects.In the microscopic scale of carbon matrices,Fe₃O₄and Fe S₂are combined through micro-coupling which can improve the catalytic ability significantly.Further,as the Fe₃O₄and Fe S₂nanoparticles were well dispersed in carbon frameworks,their possible aggregations can be effectively avoided,which will be favoable to improve the utilization rate of the catalyst.Catalytic results reveal that the catalyst can activate both peroxymonosulfate(PMS)and hydrogen peroxide(H₂O₂).When the catalyst is applied to the combined PMS/H₂O₂system for the catalytic degradation of organic pollutants,it exhibits broadened p H range of application with accelerated rate of catalytic degradation.For the degradation of Rhodamine B,it can be removed within30min completely in a wide p H range from 3 to 9.Meanwhile,the novel ternary nanocomposites can achieve high-efficiency degradation of other organic pollutants.The mechanism study indicates that there are synergistic effect between the combined systems and catalyst,which is conducive to the rapid generation of more oxidation free radicals.