Boron Atoms Doped RGO Wrapped Fe₃O₄ Nanoparticles As Heterogeneous Photo-Fenton Catalyst For Bisphenol A Degradation Under Visible Light

As a kind of advanced oxidation process,heterogeneous photo-Fenton reaction possesses the advantages of simple operation,fast reaction rate and low toxicity.However,due to the slow Fe²⁺/Fe³⁺conversion and low recycling rate,the traditional heterogeneous photo-Fenton still suffer from the limited efficiency to degrade refractory organic pollutants under visible light.In order to solve the above problems,a nanoscale magnetic material Fe₃O₄@B-r GO was prepared in this paper.It was a core-shell heterogeneous photo-Fenton catalyst with Fe₃O₄as the core and B-r GO?Boron doped reduced graphene oxide?as the shell.Through a series of systematic studies,the structural features,catalytic performance and catalytic mechanism of the catalyst were studied.The main research contents and results are as follows:?1?Core-shell structured photo-Fenton catalyst Fe₃O₄@B-r GO was successfully prepared via one-step reflux route.The crystal structure,surface morphology,chemical composition,specific surface area and pore structure of the catalyst were analyzed by X-ray diffraction,Raman spectrum,scanning electron microscope,transmission electron microscope,X-ray photoelectron spectroscopy,spherical aberration correction electron microscope and nitrogen adsorption-desorption isotherms,respectively.The X-ray diffraction,Raman spectrum,scanning electron microscope and transmission electron microscope results showed that Fe₃O₄and r GO have formed a core-shell structure successfully and the particle size were between 100nm and 300 nm.The results of X-ray photoelectron spectroscopy and spherical aberration correction electron microscope indicated that some carbon atoms in graphene structure were replaced by boron atoms.Nitrogen adsorption-desorption isotherm measurments demonstrated that Fe₃O₄@B-r GO was a mesoporous material with a specific surface area of 42.81 m²/g and pore volume of 0.136 cm³/g.?2?The optimum experimental conditions for Bisphenol A degradation under the heterogeneous photo-Fenton system using Fe₃O₄@B-r GO as catalyst were obtained.The catalytic performance of three different catalysts?Fe₃O₄,Fe₃O₄@r GO and Fe₃O₄@B-r GO?were also compared under the optimal experimental conditions which the p H was 5,H₂O₂concentration was 6 mmol/L,Fe₃O₄@B-r GO dosage was 0.4 g/L,the initial concentration of Bisphenol A was 20 mg/L and light intensity was 500 W.And the results showed that Fe₃O₄@B-r GO exihibted superior performance on the degradation rate of Bisphenol A compared to the other two kinds of catalysts.Besides,the catalytic performance of Fe₃O₄@B-r GO was greatly influented by the the boron doping concentration.When 9.3%of boron was dopped in Fe₃O₄@B-r GO,the obtained material showed the optimum catalytic performance.In the Fe₃O₄@B-r GO?9.3%?system,Bisphenol A was basically degraded after 60 min reaction under light and the mineralization rate could reach to 67.6%after 180 min.Also,the recycling experiments illustrated Fe₃O₄@B-r GO?9.3%?has good stability and recyclability.?3?The active species capture experiments,electron spin resonance,electrochemistry and density functional theory were applied to discuss the reaction mechanism of the system using Fe₃O₄@B-r GO?9.3%?as catalyst.The experiments of active species capture and electron spin resonance proved that hydroxyl radicals and superoxide radicals were the main active species.Finally,the possible simplified mechanism of the reaction system was deduced.