A highly efficient adsorption-photocatalytic synergistic degradation of tetracycline by in-situ constructed Bi5O7I/ZIF-8 heterojunction

Residue organic matter such as antibiotics and dyes are left in wastewater that are difficult to remove. Herein, we reported a bismuth oxyiodide (Bi₅O₇I)/zeolite imidazolate framework-8 (ZIF-8) catalyst with an S-scheme heterojunction for the degradation of tetracycline (TC) using an in-situ growth strategy. The degradation process of TC is divided into two parts: adsorption and photocatalysis. Under dark reaction conditions, the Bi₅O₇I/ZIF-8 composites have an eminent adsorption effect on TC. When exposed to visible light, the resulting Bi₅O₇I/ZIF-8 composites revealed an outstanding photocatalytic activity and high stability toward TC degradation. Experiments utilizing active species trapping showed that O₂ is essential to the photocatalytic process and the efficacy of the process is further improved by the addition of h⁺ and •OH. Likewise, these catalysts catalyzed the degradation of 84.6% of TC, and the Bi₅O₇I/ZIF-8 also exhibited high degradation stability after 4-cycle trial. This work optimizes the degradation performance of antibiotic residues by presenting a practical and doable approach for creating green semiconductor heterojunctions.