Peroxymonosulfate-Assisted BiVO4/Exfoliated g-C3N4 Heterojunction for High-Performance Photodegradation of Tetracycline Induced by Visible Light

Antibiotic residues entering the ecological environment not only cause serious environmental pollution but also may cause the development of resistance genes and other ecological risks. Therefore, the degradation of antibiotic contaminants has become a research hot spot. Herein, a new Z-scheme BiVO4/exfoliated g-C3N4 heterojunction photocatalyst was synthesized for efficient tetracycline photodegradation with the assistance of peroxymonosulfate under visible light irradiation. The influence of different key environmental factors, including peroxymonosulfate concentrations, coexisting ions, and solution pH, on the photodegradation efficiency of tetracycline was comprehensively studied. The optimized BiVO4/exfoliated g-C3N4–0.6 was demonstrated to exhibit excellent photodegradation performance of tetracycline with an apparent kinetic constant of ca. 0.128 min–1 with 0.3 mM peroxymonosulfate, which was ca. 3 times of exfoliated g-C3N4 (0.0415 min–1) under the same conditions and about 16 times and 5 times of bulk g-C3N4 (0.0080 min–1) and exfoliated g-C3N4 (0.0285 min–1) without peroxymonosulfate, respectively. The BiVO4/exfoliated g-C3N4–0.6 showed only about 5% reduction in the degradation efficiency of tetracycline after six consecutive cycle experiments. The free radical scavenging test and electron spin resonance characterization results suggested that •O2–, h+, •SO4–, •OH, and 1O2 were all involved in the catalytic oxidative process of tetracycline in the BiVO4/exfoliated g-C3N4–0.6, peroxymonosulfate and light reaction system. This study not only offers an attractive Z-scheme heterojunction photocatalyst for tetracycline degradation but also demonstrates a promising way to use peroxymonosulfate for advanced wastewater treatment.