| The textile industry is one of the most important economic industries in the world.Every year,a great deal of dyes were synthesized and used in printing and dyeing,and a considerable proportion of them are discharged into river water with the waste water.Synthetic dyes’ chemical structure is complex and stable,so it is difficult to use the conventional activated sludge process of biodegradation.Photocatalytic wastewater treatment technology has been attracting more and more interest from researchers in the world because of its simple operation,good handling effect and low cost.It is the key to photocatalytic technology to study a kind of photocatalyst with high efficiency,stability,low cost and strong light absorption.In this paper,the graphite phase carbonitride with visible light response was used as the object of study,and its photocatalytic activity was attempted to be enhanced by doping with nano magnet.The structure and properties of prepared materials were characterized by SEM,TEM,XRD,FTIR,DRS techniques,the best application environment of photocatalytic degradation of RhB was discussed.In this paper,the dynamic characteristics and influencing factors of photocatalytic degradation of dye wastewater were also discussed.The specific research results were as follows:1.The results of morphological characterization showed that there was strong intermolecular force between Fe3O4 nanoparticles and g-C3N4.Fe3O4 nanoparticles did not invade the lattice of g-C3N4,Fe3O4 nanoparticles were only deposited on the surface of g-C3N4,indicating that Fe3O4 and g-C3N4 formed a heterojunction structure at the interface.DRS analysis showed that the absorption of the composite was enhanced in the visible region compared with Fe3O4.The macroscopic magnetic analysis showed that the newly synthesized materials have good magnetic properties.The Fe3O4/g-C3N4 composite photocatalytic material can be separated from the reaction liquid by the external magnetic field,which solved the problem that the powder catalyst is difficult to recycle and reuse.2.Photocatalytic experiments results showed that the photocatalytic activity of Fe3O4/g-C3N4 was 17.7%and the degradation rate of RhB reached 96.2%under visible light irradiation for 2 hours.However,the photocatalytic activity of Fe3O4/g-C3N4 composite photocatalyst decreased when the nanoparticles and g-C3N4 were simply mixed or when Fe3O4 exceeded a certain limit.The photo-generated electrons are transferred to the conduction band of Fe3O4,which hinders the separation of the photo-generated electrons from the holes and leads to the decrease of the photocatalytic activity of Fe3O4/g-C3N4.In addition,the photocatalytic degradation rate of RhB in alkaline solution was increased from 71.4%to 95.7%when Fe3O4/g-C3N4 nano-composite photocatalyst was prepared.The photocatalytic activity of the photocatalyst can be improved by increasing the amount of the photocatalyst.The excessive photocatalytic activity will result in the decrease of the photocatalytic activity.3.Photocatalytic degradation of RhB dye wastewater by magnetic nanocomposite photocatalyst Fe3O4/g-C3N4 conformed to the first order reaction kinetics model.The results showed that the reaction rate constant K of photocatalytic degradation of RhB dye decreased with the increase of Fe3O4 mass fraction of Fe3O4/g-C3N4 composite. |
PDF Full Text Request