The Synthesis Of TiO₂@Fe₃O₄/GO Powder And Its Photocatalytic Degradation Of Polycyclic Aromatic Hydrocarbons

With the vigorous development of industrialization,energy and environment are facing severe tests,and water pollution has become an urgent problem to be solved.Magnetic-semiconductor photocatalytic adsorption and degradation technology provides new solutions to energy and environmental problems.In this thesis,a magnetic adsorption degradation material was synthesized,and the performance of the material and its ability to adsorb and degrade organic pollutants polycyclic aromatic hydrocarbons were studied.Fe₃O₄was prepared by co-precipitation method,and the effects of Fe²⁺/Fe³⁺ratio,p H value and reaction temperature on the magnetic properties of the prepared samples were investigated.The study found that the obtained Fe₃O₄powders are all inverse spinel type,spherical particles with a size of 150-200 nm.As the ratio of Fe²⁺/Fe³⁺increases,the saturation magnetization,coercive force and residual magnetization all show an increasing trend.Among them,when the p H value is10-11,a higher saturation magnetization is obtained.When the reaction temperature is 80℃,the saturation magnetization is 70 emu/g and the coercivity is about 150 Oe,which is 15 emu/g higher than that of the saturation magnetization at 60℃,and the coercive force increases by 20 Oe.The core-shell structured TiO₂@Fe₃O₄composite powder was prepared by the sol-gel method.The study found that the introduction of Fe₃O₄caused a decrease in the band gap width and the recombination rate of photogenerated carriers,and increased the light response range of TiO₂,but the saturation magnetization decreased significantly.Comparing the adsorption and degradation ability of pure TiO₂,Fe₃O₄and composite powder,the removal efficiency of anthracene from composite powder reached 66%within 100 min,slightly weaker than that of the pure TiO₂（removal efficiency of 70%）,and higher than Fe₃O₄（removal efficiency of 60%）.TiO₂@Fe₃O₄composite powder and GO prepared by Hummer method were composited by mechanical mixing to obtain TiO₂@Fe₃O₄/GO composite powder.The results reveal found that the amount of GO added in the experiment has little effect on the magnetic properties of the composite powder.Compared with TiO₂@Fe₃O₄composite powder,the adsorption capacity are improved.After 5 cycles of catalytic degradation experiments,the removal efficiency of PAHs still reached73.4%.Before adding the photocatalyst TiO₂@Fe₃O₄/GO composite powder to the PAHs solution,introduce disodium ethylenediaminetetraacetate（EDTA-2Na）,tert-butanol（TBA）,and ascorbic acid（AA）as cavities（h⁺）,hydroxyl radicals（·OH）,superoxide radicals（·O₂^-）traps,the results reveal that the main groups playing the major role in the photocatalytic degradation of PAHs are·O₂^-and·OH.