Z-scheme heterojunction composed of Fe doped g-C3N4 and MoS2 for efficient ciprofloxacin removal in a photo-assisted peroxymonosulfate system

Herein, a series of Z-type heterojunctions Fex[email protected]2-Y were synthesized by a combination of calcination and hydrothermal methods for the removal of ciprofloxacin (CIP) by peroxymonosulfate (PMS) activation under visible light. It was optimized that Fe3[email protected]2-4 exhibited excellent photocatalytic performance, with the degradation rate of CIP 84 % within 140 min. Besides, its rate constants were 23.74, 3.59, and 3.98 times higher than those of pure g-C3N4, Fe3CN, and MoS2, respectively. Furthermore, the Fe3[email protected]2-4/PMS/vis system could efficiently degrade other antibiotics (enrofloxacin (ENRO), metronidazole (MNZ) and tetracycline (TC)). The quenching experiments and electron paramagnetic resonance (EPR) characterization showed that reactive substances such as 1O2, h+ and Ovs played a dominant role in this system. We deeply explore the possible mechanisms and CIP degradation pathways for the enhanced CIP degradation efficiency in the Fe3[email protected]2-4/PMS/vis system. Among them, the exposed Mo (IV) and Fe (II) sites on the catalyst surface accelerated the electron transfer, while the S2- therein promoted the cycling between ions, thus increasing the reaction rate. Finally, Fe3[email protected]2-4 maintained appreciable performance even after 5 cycles. This study may provide a new approach for the development of metal-doped g-C3N4-based complexes.