Synthesis of magnetic PPAC@Fe3O4@MOF S-scheme heterojunction catalyst with enhanced removal of metronidazole antibiotic under visible light

Abstract

In the present investigation, Fe-MOF decorated magnetic pomegranate peel activated carbon (PPAC) was synthesized using the two-step method, and different characterization studies confirmed the successful preparation of the PPAC@Fe₃O₄@MOF (PPACFM) nanocomposite. The photocatalytic activity of the PPACFM was evaluated using metronidazole (MNZ) antibiotic as a representative organic pollutant under visible light irradiation. The PPACFM nanocomposite achieved an impressive 99.4 % degradation of MNZ within 60 min when the concentration of MNZ was 30 mg/L, the catalyst dosage was 2 g/L, the pH value was 5, and the light power was 100 W. The results showed that the incorporation of inorganic salt ions had a discernible effect on the photocatalytic removal performance. The formation of an S-scheme heterojunction between PPAC@Fe₃O₄ and MOF was confirmed by active oxygen species trapping experiments. This heterojunction promoted electron-hole separation, which in turn improved the photocatalytic performance of MOF. Also, the catalyst maintained its excellent performance over four consecutive cycles, indicating its high reusability and stability. Hence, the PPACFM nanocomposite utilized in this study provides a valuable starting point for both the development of novel photocatalysts and the practical implementation of photocatalytic removal technology in purifying pharmaceutical wastewater.