Preparation And Properties Of Coated Graphene/TiO₂ Magnetic Composite Photocatalyst

In order to prepare a TiO₂ photocatalyst that can be separated and recovered with high photocatalytic performance,this paper firstly prepared the graphene oxide solution by the modified Hummers method,then prepared the magnetic matrix by coprecipitation method,and finally prepared different kinds of magnetic composite photocatalyst by hydrothermal method.The catalytic performance and recycling performance of the composite photocatalyst were evaluated by performing a series of characterization analysis on the sample and the degradation rate of methyl orange solution under ultraviolet light.Finally,the kinetic characteristics and photocatalytic mechanism of photocatalytic degradation of methyl orange dye wastewater by synthetic magnetic composite photocatalyst were represented by T/G-F1.The experimental results showed that:?1?In the magnetic composite photocatalyst with different graphene contents,when the concentration of graphene oxide solution is 0.75mg/mL,the obtained magnetic composite photocatalyst T/0.75G-F has better catalytic performance and magnetic properties.XRD and TEM analysis showed that the TiO2 formed in the prepared magnetic composite photocatalyst was anatase phase and Fe₃O₄ was cubic crystal,and both of them were uniformly dispersed on the surface of rGO sheet;BET results showed that the specific surface area and pore volume of magnetic composite photocatalyst T/0.75G-F were the largest,which were 238.3703 m²/g and 0.578432 cm³/g,respectively;UV-visDRS results showed that the absorption of visible light by magnetic composite photocatalyst was significantly enhanced,and the red shift was observed in the visible region.The red shift of T/0.75G-F was the largest,which was consistent with the BET results.In the experiment of photocatalytic degradation of methyl orange solution,the degradation rate of T/0.75G-F to methyl orange solution was the highest at 94.58%,and the degradation rate could still reach90.87%after repeated use for five times.?2?In the magnetic composite photocatalyst with different ratio of TiO2 and magnetic matrix,when the ratio is 3:1,the obtained magnetic composite photocatalyst T/G-F1 has better catalytic performance and magnetic properties.XRD and EDS analysis showed that the TiO₂/rGO-Fe₃O₄ magnetic composite photocatalyst was successfully synthesized.It can be clearly seen from the TEM image that the ratio of TiO2 to magnetic matrix was 3:1,and the TiO2 and Fe3O4 particles formed by the reaction were more uniformly dispersed between the rGO sheets;BET results showed that the specific surface area and pore volume of TiO2 had increased significantly after the introduction of rGO,and the specific surface area and pore volume of T/G-F1 were the largest in the composite photocatalysts with different ratios;UV-visDRS results showed that T/G-F1 had the strongest response to visible light,and its forbidden band width was only 2.52 eV compared with pure TiO₂;VSM results showed that T/G-F1 had good magnetic properties and its saturation magnetization was 6.47emu/g at room temperature.In the experiment of photocatalytic degradation of methyl orange solution,T/G-F1 had the best degradation effect and the degradation rate was as high as 94.94%.After repeated use for five times,the degradation rate of methyl orange solution could still reach 90.23%.?3?The degradation reaction of magnetic composite photocatalyst T/G-F1 on methyl orange solution is first-order reaction,and follows the Langmiur-Hinshelwood?L-H?kinetic model.The degradation kinetic equation is:r=C₀/?88.45206+1.42908C₀?.The results show that the magnetic composite photocatalyst prepared by changing the concentration of graphene oxide solution and the ratio of TiO₂ to magnetic matrix has high photocatalytic performance and can be separated and recycled.It has guiding significance for realizing the comprehensive promotion and large-scale application of TiO₂ photocatalysis technology.