Ag2O modified magnetic BaFe12O19/C3N4 photocatalysts with enhanced antibiotic removal: Photocatalytic mechanism and toxicity evaluation

Novel Ag₂O-BaFe₁₂O₁₉/C₃N₄ composites were prepared via a grind, solvothermal and deposition–precipitation methods. The physicochemical properties of the samples were tested by FT-IR, XRD, SEM, TEM, XPS, DRS, ESR, VSM, photocurrent test, and electrochemical impedance spectra test, respectively. The characterization manifested that Ag₂O was firmly anchored to the BaFe₁₂O₁₉/C₃N₄ to form heterogeneous hybrid. Most importantly, the formation of Ag₂O-BaFe₁₂O₁₉/C₃N₄ effectively promoted the charge transfer, eventually enhancing the photocatalytic performance. Meanwhile, the activity of the photocatalysts were assessed by photocatalytic removal of tetracycline (TC) under visible light irradiation. The results showed that Ag₂O-BaFe₁₂O₁₉/C₃N₄ photocatalyst has better photocatalytic activities than the pure component. The degradation rate reaches 80 % after 15 min, which is nearly 1.56 times higher than that of pure g-C₃N₄. The effects of Ag₂O content, photocatalyst dosage, pH value on TC degradation performances were studied in detail, respectively. The experimental results verified that pH value exhibited significant effects on TC degradation. The TC degradation rate was highest only when the initial solution pH = 7. This indicates that the photocatalyst also has high activity in neutral environment, and no additional pH adjustment is required. The results of plant growth test (mung bean seeds) showed that the degradation intermediates showed lower toxicity. Based on experiments and characterization, the possible carrier migration and photocatalytic degradation mechanism were proposed.