Efficient photocatalytic degradation of doxycycline by coupling α-Bi2O3/g-C3N4 composite and H2O2 under visible light.

Antibiotic pollutants have posed a huge threat to the ecological environment and human health. In this work, α-Bi2O3/g-C3N4 composite was prepared and coupled with H2O2 for the rapid and efficient degradation of doxycycline (DOX) in water under visible light irradiation. The composite exhibited enhanced photocatalytic activity and 80.5% of DOX could be degraded in 120 min. The addition of H2O2 significantly improved the degradation efficiency of DOX under visible light, resulting in 79.0% of it degraded within 30 min, and the degradation rate constant of DOX was 3.6 times than that without H2O2. On the one hand, the Z-scheme heterojunction of α-Bi2O3/g-C3N4 promoted the separation rate of photogenerated electron-hole pairs, thereby enhancing the photocatalytic activity of the composite. On the other hand, the improvement of photocatalytic efficiency also benefited from the extra hydroxyl radicals generated by the reaction of photogenerated electrons with H2O2 in the photocatalytic system. Free radicals trapping experiments and electron spin resonance tests proved that played prominent role in the degradation process. After adding H2O2, OH also became important active species. Cyclic degradation experiments demonstrated the recyclability of the composite photocatalyst in DOX elimination applications. This work provides an efficient, clean, and recyclable purification strategy for removing antibiotic contaminants from water.