Recyclable MXene-bridged Z-scheme NiFe2O4/MXene/Bi2WO6 heterojunction with enhanced charge separation for efficient sonocatalytic removal of ciprofloxacin.

ABSTRACT

Sonocatalysis has emerged as a promising technology for addressing environmental pollution issues. However, the efficacy of sonocatalytic processes is primarily hindered by challenges related to the sluggish flow rate of photogenerated electrons. This study presents a novel approach to address this issue by developing an improved Z-scheme NiFe2O4/MXene/Bi2WO6 (NMB) composite that exhibits exceptional sonocatalytic activity for ciprofloxacin (CIP) degradation. In particular, the NiFe2O4/MXene (5 wt%)/Bi2WO6 composite could achieve high CIP (at 10 mg/L) degradation efficiency (97.39 %) after 60 min of ultrasonic irradiation. The exceptional sonocatalytic activity of the composite was attributed to the synergistic interaction of the Z-scheme heterojunction charge transfer route and the electron mediator of Ti3C2-MXene, which enhances light collection capacity, separates photogenerated carriers efficiently, and improves redox activity of the composite. The scavenging experiments reveal that the sonocatalytic degradation of CIP was driven by holes (h+), hydroxyl radicals (•OH), and superoxide anion radicals (•O2-), with the former playing a dominant role. The results of reuse experiments demonstrate the outstanding sonocatalytic stability of the catalyst, as well as its uncomplicated recovery. The developed NMB Z-scheme composite shows promise for sonocatalytic treatment of antibiotics in industrial wastewaters, particularly those with high turbidity and/or low transparency. The findings also open up avenues for developing efficient and cost-effective sonocatalysts with good recyclability and remarkable performance.