Performance Of Magnetic Iron Based Composite Catalyst In Advanced Oxidation Process

In recent years,with the continuous development of printing and dyeing technology,the processing types and difficulties of organic pollutants have increased,and the concentration of pollutants has also increased significantly.Advanced oxidation method has become an effective way to deal with organic pollutants.In order to solve the problem of catalyst recovery in the process of pollutant treatment.In this thesis,the magnetic oxide Fe₃O₄ was selected as the matrix,which was compounded and loaded with BiOBr and porous diatomite respectively,build the Bi-BiOBr/Fe₃O₄ and BiOBr-Fe₃O₄@D two kinds of ternary catalytic system.Rhodamine B（Rh B）was used as the degradation target and peroxymonosulfate（PMS）was added to form an advanced oxidation system.Under visible light irradiation,the catalytic performance of the catalytic system was tested,the best catalytic conditions were determined,the efficient catalyst was searched,and the catalytic mechanism of the catalyst in the process of advanced oxidation was explored.The research contents are as follows:（1）Bi-BiOBr/Fe₃O₄and BiOBr-Fe₃O₄@D catalysts were synthesized by hydrothermal method.The catalysts were characterized by a series of testing methods,and the phase composition and morphology of the two catalysts were analyzed.The results showed that two kinds of composite catalysts were successfully prepared with complete structure,high purity and high saturation magnetization.（2）The photocatalytic performance of the Bi-BiOBr/Fe₃O₄and BiOBr-Fe₃O₄@D for Rh B was investigated.The effects of different systems,catalyst dosage,initial p H value of solution,PMS concentration and other catalytic on the degradation rate and recycling performance of Rh B were studied.Under the same conditions,the degradation rate of Bi-BiOBr/Fe₃O₄ catalyst reached 98.52%in 80min photocatalysis.The degradation rate of Rh B by BiOBr-Fe₃O₄@D reached99.32%in 30 min.After 5 cycles of degradation,the degradation rate of the Bi-BiOBr/Fe₃O₄and BiOBr-Fe₃O₄@D catalyst was 92.12%and 96.86%respectively.（3）The types of active substances and degradation pathways of Bi-BiOBr/Fe₃O₄and BiOBr-Fe₃O₄@D catalysts in the photoassisted advanced oxidation process were investigated,and the degradation mechanism was analyzed.The results show that·OH,SO₄^-·,h⁺are the dominant free radicals in the catalytic process of Bi-BiOBr/Fe₃O₄ catalyst,and·OH and SO₄^-·are the dominant free radicals in the catalytic process of BiOBr-Fe₃O₄@D catalyst.In the photodegradation of Rh B by Bi-BiOBr/Fe₃O₄and BiOBr-Fe₃O₄@D catalyst,there are seven kinds of intermediates,which mainly include four processes:N-deethylation reaction,destruction of chromoconjugate structure,ring-opening reaction and mineralization.（4）The experimental results show that the performance of BiOBr-Fe₃O₄@D catalyst is better than that of Bi-BiOBr/Fe₃O₄ catalyst.