Study on Preparation of BiFeO3/Bi2Fe4O9 Composite Photocatalyst and Photocatalytic Degradation of Various Organic Dyes in Waste Water

BiFeO3/Bi2Fe4O9 composite photocatalyst was prepared by one-step sol–gel method. The phase structure, morphology, optical properties and photocatalytic activity of Bi2Fe4O9 and BiFeO3/Bi2Fe4O9 composite photocatalyst have been systematically studied. The introduction of excessive Bi and Fe nitrate into Bi photocatalyst effectively enhanced the light absorption capacity of BiFeO3/Bi2Fe4O9 composite photocatalyst. The effects substrate nature on photocatalytic activity of BiFeO3/Bi2Fe4O9 composite photocatalyst were studied with methyl orange (MO), methyl blue (MB), rhodamine B (RhB), methyl red (MR), acid red (AR), and Congo red (CR) as the target degradation dyes. The effects of dye concentration, catalyst content and pH on photocatalytic activity of BiFeO3/Bi2Fe4O9 composite photocatalyst were systematically studied with methyl orange as the main degradation dye. Photocatalytic experiments showed that the optimal dye concentration, catalyst content, and pH value were 15 mg/L, 20 mg/L, and 5, respectively. In the whole photocatalytic reaction process, hole, and hydroxyl radical play the most important role.