Photo-electrochemical Degradation Of Pollutants In Water By Electrodes With G-C₃N₄/Bi₂WO₆

In recent years,with the advancement of global science and technology and the development of industry,human beings have increasingly damaged the ecological environment,which has posed a threat to human survival and health.Therefore,ecological protection and pollution restoration have become the focus of worldwide attention.Photo-electro-catalysis technology is a catalytic reaction technology based on photocatalysis and electrochemistry.With its good catalytic degradation performance,it is widely used in the removal and treatment of pollutants.However,most of the current photocatalytic materials have low light utilization rate,and the degradation efficiency does not meet the requirements.In particular,the performance of degrading new perfluorinated pollutants needs to be improved,and the technology is also greatly restricted in practical applications.Therefore,in this paper,a new electrode catalytic material containing g-C₃N₄/Bi₂WO₆ catalyst was studied,and two self-biased photoelectrochemical?PEC?systems without external power supply were constructed to degrade and purify pollutants in water,especially For rhodamine B?RhB?and perfluorooctane acid?PFOA?,the degradation and purification efficiency of the system under different reaction conditions were evaluated,and the reaction mechanism of the system was discussed.The main results of the research are:?1?The high-temperature hydrothermal method was used to prepare g-C₃N₄/Bi₂WO₆ and porous carbon nanosheets?PCN?modified PCN/g-C₃N₄/Bi₂WO₆ composite catalyst,and the catalyst electrode was supported on the stainless steel net by neutral silica sol.The catalytic electrode was characterized and analyzed by various technical means?XRD,SEM,TEM,UV-vis,XPS,CV?.The analysis showed that the target catalyst has good crystallinity and superior photoelectric performance.?2?A binary g-C₃N₄/Bi₂WO₆ catalyst was prepared,supported on a stainless steel mesh with silica sol as a photoanode,and a PEC system constructed with a carbon rod as a cathode was studied.When Rhodamine B was used as the target pollutant The effects of external resistance,initial pH of the solution and aeration on the system efficiency were discussed.When the external resistance of the system was 1000?and the solution was acidic and aerated,the removal rate of RhB can reach about 90.6%after 60 minutes of reaction,which proved that the system has good catalytic performance.?3?A self-biased photoelectric catalytic PEC system with a three-way catalyst PCN/g-C₃N₄/Bi₂WO₆ stainless steel mesh as the cathode and iron rod as the anode was constructed.When the iron rod is the anode,the external resistance was 1000?and the pH was 7,the removal efficiency of PFOA can reach 88.4%within 30 minutes.The catalytic activity of this system had not decreased in repeated experiments,showed excellent stability.The results of quenching experiments and EPR test experiments showed that the main active substances in the degradation process of PFOA were superoxide radicals and photogenerated holes.When ferrous iron and zero-valent iron were present,the generation of free radicals by bisulfite also accelerated the degradation rate and improved the photocatalytic degradation efficiency.The possible degradation pathway of PFOA in PEC system was proposed.The degradation of PFOA was carried out by removing PFCA molecules one molecule at a time to form a shorter chain.In summary,the two kinds of composite catalysts,catalytic electrodes and photocatalytic system constructed have a good degradation effect on pollutants in water,which has raised new ideas for the photoelectric catalytic technology to efficiently remove pollutants in water.