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

The proposed photocatalytic mechanism of Ag2O-BaFe12O19/C3N4 under visible light illumination, and the results of plant growth test (mung bean seeds) showed that the degradation intermediates showed lower toxicity. [Display omitted] •Novel Ag2O-BaFe12O19/C3N4 composites were successfully prepared.•The degradation rate of Ag2O-BaFe12O19/C3N4 for tetracycline improved obviously.•The LSPR effect of Ag2O can improve the efficiency of electron hole separation.•The degradation intermediates have lower or no toxicity to plants growth. 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.