Highly efficient visible-light-driven photodegradation of tetracycline via flower-like BiOBr/g-C3N4 heterojunction

Herein, a BiOBr/g-C 3 N 4 heterojunction was effectively synthesized using a hydrothermal method and applied to investigate the photodegradation of tetracycline antibiotic (TC). The obtained BiOBr/g-C 3 N 4 presented a high purity and porous material, with a specific surface area of 9.72 m 2 /g and an average pore diameter of 35.79 nm. A flower-like structure of BiOBr was relatively uniform and well dispersed on g-C 3 N 4 nanosheets. BiOBr/g-C 3 N 4 heterojunction was a visible light-driven photocatalyst, with a band gap energy of 2.38 eV, delivering superior TC degradation performance, with 1.55–4.09 times higher than individual materials. Influence of critical parameters including pH, catalyst dosage, TC concentration, and co-existing ions on the photocatalytic efficiency were comprehensively examined, with a TC degradation efficiency reached 96.53 ± 2.03% by visible light under optimized conditions ([BiOBr/g-C 3 N 4 ] = 0.5 g/L, pH 7.0, and 10 mg/L TC). About 55% of TOC was treated in wastewater due to the presence of other organic compounds, co-existing ions, and high turbidity of the wastewater. The pseudo-first-order kinetics (R 2 = 0.930 – 0.996) best described the TC degradation process, with a rate constant (k) within 0.005 – 0.0035 min −1 . The photocatalyst was easily recovered and reused, retaining over 80% of its initial performance after five consecutive treatment cycles.