Study On The Synthesis And Photocatalytic Performance Of Fe₃O₄/g-C₃N₄ Composite Photocatalyst

In recent years,graphite carbon nitride?g-C₃N₄?has been used for visible light because of its suitable forbidden band width,which greatly improves the utilization ratio of sunlight.And its constituent elements are abundant in nature.Therefore,g-C₃N₄ attracts much attention.However,as a photocatalyst,g-C₃N₄ still has some problems,such as photoelectron hole recombination rate,recycling difficulties and low repetition rate.These problems have been urgent problems for researchers.In view of the problems existing in the above g-C₃N₄,In this paper,melamine,urea as precursor by high-temperature calcination method,the preparation of g-C₃N₄ monomer significantly,plate-like morphology;In the preparation of Fe₃O₄,Fe₃O₄ microspheres with uniform particle size and ferromagnetic properties were prepared by using hexahydrate ferric chloride as an iron source,ethylene glycol as a reaction solvent,polyethylene glycol as a dispersant,and solvothermal method.In the composite material,Fe₃O₄/g-C₃N₄ magnetic composites and g-C₃N₄/TiO₂ composites and Fe₃O₄/g-C₃N₄/TiO₂ ternary composite catalyst were synthesized by high temperature calcination.By using X-ray diffraction?XRD?,Fourier transform infrared spectrometer?FT-IR?,infrared spectroscopy UV-Vis diffuse reflectance spectroscopy?UV-Vis/DRS?,scanning electron microscopy?SEM?and vibrating sample magnetometer?VSM?and other methods on the phase composition,different samples of each stage of surface properties,morphology and magnetic strength were characterized;methylene blue?MB?as the model pollutant,the photocatalytic activity of the catalyst samples using the evaluation of each stage,include the Fe₃O₄/g-C₃N₄ and Fe₃O₄/g-C₃N₄/TiO₂ composite magnetic recovery performance.Through the study,the following conclusions are obtained:1.The Fe₃O₄/g-C₃N₄ magnetic composites prepared by high-temperature calcination,Fe₃O₄ micron particles were uniformly distributed on the surface of g-C₃N₄ sheet structure,is advantageous in the visible light irradiation,g-C₃N₄ photoinduced electron transfer,thus improving the Fe₃O₄/g-C₃N₄ composite visible light catalytic activity;at the same time using the magnetic properties of Fe₃O₄,to achieve the Fe₃O₄/g-C₃N₄ the magnetic composite material recycling and recycling;2.The visible light photocatalytic degradation of MB by Fe₃O₄/g-C₃N₄ magnetic composites prepared by g-C₃N₄ and Fe₃O₄,discussed the different quality of the composite ratio,calcination temperature,time,catalyst dosage,MB initial concentration,pH and so on catalytic activity influence,at the same time on the catalytic reaction of preliminary mechanism study.The results show that:1)In Fe₃O₄/g-C₃N₄ composites,when the mass ratio of Fe₃O₄ to g-C₃N₄ is 1:4,the composite has the highest catalytic activity,but the recovery performance of the composites is weak.The final mass ratio of 1:3 is selected.As the best ratio,at this time,for the MB solution with an initial concentration of 10 mg/L,the visible light degradation rate of the simulated contaminants in the 1g/L g-C₃N₄/Fe₃O₄ composite material was 59.9%within 120min.2)When the initial concentration of MB was 10 mg/L,through the single factor experiment,the optimum calcination temperature is 450°C,the best calcination time is 2h,and 1g/L is the best dosage of the catalyst.3)Through repeated recycling of the Fe₃O₄/g-C₃N₄ composite material,it was concluded that after recycling five times,the magnetic recovery efficiency of the catalyst is still above87%,with stable magnetic recovery performance.The photocatalytic degradation of the catalyst resulted in the loss of Fe₃O₄,and the catalytic activity of the composite catalyst after recycling decreased by 46%.3.The g-C₃N₄/TiO₂ composite catalyst prepared by high-temperature calcination has good catalytic activity,and the highest catalytic activity is obtained when the mass ratio of g-C₃N₄/TiO₂ is 4:1.4.The Fe₃O₄/g-C₃N₄/TiO₂ ternary composite catalyst prepared in this paper possesses at the same time has high magnetic recovery and catalytic activity.