Preparation Of Bismuth-based Composites And Their Photofenton Degradation Properties Of Rhodamine B

The discharge of dye wastewater and its environmental pollution has garnered worldwide attention,and finding efficient ways to degrade it has become a major challenge in the field of environmental management.Although the traditional Fenton method is widely used in sewage treatment,it has limitations such as a narrow pH range,slow metal ion circulation rate,and inability to recover catalysts.Research has shown that combining photocatalysis and the Fenton system has a significant synergistic effect,improving the degradation of organic pollutants.Bismuth-based semiconductor photocatalytic materials are promising due to their stable chemical properties,easy regulation,and simple synthesis conditions.However,their photocatalytic activity is limited by the recombination of photo-generated electron holes and slow migration rates.To address these issues,this study modifies bismuth oxide bismuth molybdate（Bi₂Mo O₆）and bismuth tungstate（Bi₂WO₆）through a hydrothermal method,and constructs heterojunction photocatalysts with layered double metal hydroxides（LDHs）to explore their catalytic activity in the photocatalytic Fenton system for degrading rhodamine B（Rh B）.First,a Co Al-LDH/Bi₂Mo O₆ composite material is prepared by adjusting the mass ratio of Co Al-LDH to Bi₂Mo O₆ using a hexadecyl trimethylammonium bromide（CTAB）assisted hydrothermal method.The composite material exhibits the best photocatalytic activity when the mass ratio of Co Al-LDH to Bi₂Mo O₆ is 20%.At pH 6,H₂O₂ concentration of 5 mmol/L,and dosage of 0.6 g/L,the degradation efficiency of Rh B by the composite material reaches 97.8%within 60 minutes,with a rate constant2.98 times that of pure Bi₂Mo O₆.XRD,SEM,and XPS are used to confirm the successful composite of the material.The electrochemical test results indicate that the formation of heterojunctions effectively improves the charge separation and transfer rate of the catalyst.Furthermore,after five repeated experiments,the photocatalyst maintains high degradation activity,indicating that Co Al-LDH/Bi₂Mo O₆ has strong stability.Next,a Ni Al-LDH/Bi₂WO₆ heterojunction photocatalyst is constructed by hydrothermal method,and its catalytic performance is tested to explore the effects of catalyst mass ratio,pH,H₂O₂ concentration,and catalyst dosage on degradation efficiency.Through the photo Fenton activity test,it is found that after 70 minutes of xenon lamp illumination,the degradation activity of Ni Al-LDH/Bi₂WO₆ composite photocatalyst for Rh B is significantly improved,with a degradation rate of about 98.1%.UV visible diffuse reflectance spectroscopy analysis reveals that the light absorption ability of heterojunction photocatalysts has been enhanced.Finally,possible degradation mechanisms are proposed by combining optical characterization,electrochemical testing,and free radical capture experiments.Free radical capture experiments show that h⁺、·O₂^-and·OH are the main active species.The composite catalyst enhances its light absorption ability,and its photo-generated electrons accelerate the conversion of high and low valence metal ions,react with H₂O₂to generate more strong oxidizing substances,and promote the catalytic activity of the photo Fenton system.