Harnessing light: advanced photodegradation of tetracycline using NH2-MIL-101(Cr)@ZIF-67 in water

Abstract

Antibiotic contamination in aquatic environments poses significant threats, including the emergence of antibiotic-resistant bacteria and the disruption of aquatic ecosystems. This study explores the photodegradation of tetracycline, a widely utilized antibiotic, utilizing NH₂-MIL-101(Cr)@ZIF-67 as a photocatalyst. Various characterization tests were conducted to validate the photocatalyst including FT-IR, XRD, BET, TGA, FE-SEM, and TEM images which prove the accurate synthesis of the core–shell. Experiments were conducted under controlled conditions: pH 5, a photocatalyst dosage of 30 mg, an initial concentration of 40 ppm, and a reaction duration of 30 min. The core–shell NH₂-MIL-101(Cr)@ZIF-67 photocatalyst demonstrates high efficiency about 95.2% of degrading tetracycline through a hole-mediated mechanism. Upon light irradiation, the material generates electron–hole pairs, with holes oxidizing adsorbed tetracycline molecules. The introduction of NH₂ functional groups enhances photocatalytic efficiency by facilitating electron transfer, ROS generation, and adsorption capacity. This photocatalytic process involves the adsorption of tetracycline, the generation of holes, the oxidation of tetracycline molecules, and their ultimate mineralization into less harmful byproducts. The antenna effect, where amine groups within MOFs absorb light and transfer electrons to catalytic sites, further contributes to the enhanced photocatalytic activity. Furthermore, regeneration tests explained that NH₂-MIL-101(Cr)@ZIF-67 shows significant stability which was further proved by PXRD pattern.