Preparation And Catalytic Degradation Performance Of Graphene Oxide-Fulvic Acid Composite Materials

Methylparaben(MP)is currently considered as an antimicrobial preservative and has been widely used in industrial products,food products and personal care products.MP is very common in the water environment and cosmetics ingredients which is a typical emerging environmental pollutants.MP ubiquitous in a variety of environmental media,because of its extensive use,although it is easily biodegradable,it leads to its pseudo persistence in the environment.Although the concentration of MP in the environment is not high,it is still necessary to be aware of the adverse effects of long-term accumulation on the environment.Photocatalysis is a technology to degrade wastewater by light,which is easy to operate,has high removal effect on pollutants,consumes low energy,and does not cause secondary pollution to the environment that provides an important basics to realize the environmentally friendly sustainable development road.Graphene oxide(GO)has become a good carrier of many materials with its unique layered structure and a large number of surface functional groups,and it complements with other materials to make up for its own shortcomings and achieve complementary advantages,therefore,a large number of new GO materials have been developed and widely used in the field of photocatalysis.In this thesis,we studied the self-assembly composite material of natural macromolecular organic matter FA that has strong photosensitivity and graphene oxide as a feasible technique for photocatalysis of MP,by which the GO-FA composite photocatalyst and magnetic GO-FA composite photocatalyst were prepared respectively,In addition,the photocatalytic performance and degradation capacity of the two composite photocatalysts were studied by using MP as simulated wastewaterthe.The specific content is as follows:(1)A novel composite photocatalytic material,GO-FA,was synthesized by immobilizing fulvic acid on graphene oxide by a convenient self-assembly method.Simultaneously,it was characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),Fourier transform infrared spectroscopy(FTIR),UV-vis diffuse reflectance spectroscopy(UV-vis DRS and a series of tests.The results showed that the FA particles were wrapped on the surface of graphene oxide,and the crystal form of GO material did not change after the loading of FA,and the composite material has better light absorption ability,thus improving the photocatalytic efficiency.In this paper,Methylparaben was used to simulate wastewater to study the effects of the ratio of composite material,solution p H,material dosage and initial MP concentration on the degradation rate.In line with the results of single factor experiment,three factors including the ratio of composite material,p H and material dosage were selected to conduct response surface analysis and optimization in three horizontal directions.Thus,the optimal process conditions of response surface test can be obtained: p H of solution was 3,ratio of composite material was 3 and dosage was 0.01 g.Under the optimal conditions,MP photodegradation experiments were carried out,and the results displayed that the degradation rate of MP was up to 82% after 60 minutes under UV light.Studies have shown that the catalytic activity of GO-FA composite material is higher than that of pure FA and GO,not only because of the higher adsorption capacity of GO-FA,but also due to the good light utilization of the composite material,so it is an effective photocatalyst.(2)Hot solvent method was used to synthesis a new type of magnetic graphene oxide fulvic acid ternary composite material,of which structure characteristics were analyzed by application of SEM,XRD,XPS,FTIR,UV-vis DRS and a variety of characterization methods.The characterization indicated the presence of Fe3O4 in the prepared catalytic material,which was manifested the successful preparation of magnetic GO and the successful adhesion of FA.Moreover,it was found that the photon-absorbing ability of the material was enhanced after the introduction of Fe3O4,and the composite material greatly promoted the separation and transfer of photogenerated electrons,which played an important role in the degradation process of pollutants.Macroscopic magnetic analysis proved that the magnetic GO-FA had good magnetism and was easy to recover and the cycle test showed that the degradation rate of the material could still reach 71% after four times of recovery.In this paper,Methylparaben was used to simulate wastewater to study the effects of the ratio of composite material,p H,dosage of composite material and initial MP concentration on the degradation rate and according to the results of single factor experiment,three factors of the ratio of composite material,p H and dosage of catalyst were selected to conduct response surface analysis and optimization in three horizontal directions.MP photodegradation experiments were carried out under optimal conditions and the results showed that when the initial MP concentration was20 mg/L,p H was 3,the ratio of the composite material was 3,and the dosage was0.01 g,the degradation rate of MP was up to 97% after 60 minutes under UV light.Compared with the recovery rate of the material without magnetic addition,the recovery rate is not only simple,but also increased by nearly 15%.