Study on the Photocatalytic Degradation of Rhodamine B by g-C3N4/Bi2Fe4O9 Heterojunction Photocatalyst

g-C3N4/Bi2Fe4O9 composite photocatalysts were prepared by the mechanica mixing-calcination method. The heterojunction structure formed by the composite of the two materials made it difficult for photogenerated electrons and holes to reunite and improved the degradation rate of RhB. At 60 min, the adsorption rate of 25%-g-C3N4/Bi2Fe4O9 was higher than that of Bi2Fe4O9 and g-C3N4, and the adsorption rate reached 33.33%. At 240 min, 25%-g-C3N4/Bi2Fe4O9 photocatalytic degradation efficiency of 10 mg/L RhB was good, reaching to 87.59%. The reaction rate constant was 0.00674 min−1, which was 2.53 times and 2.32 times that of Bi2Fe4O9 and g-C3N4. Superoxide radical (O2−·) and ·OH were the main active components in the dye degradation process.