Enhanced PMS activation by Mn2O3-loaded h-BN for levofloxacin removal: Unveiling the dominant influence of non-free radical pathway and N-Mn-mediated promotion of stable, long-lived Mn(IV) species

Abstract

The Mn2O3-loaded hexagonal boron nitride (h-BN-Mn) catalyst for peroxymonosulfate (PMS) activation was successfully synthesized using a one-step calcination process. The h-BN-Mn/PMS system achieved an impressive 97 % levofloxacin removal within a mere 90-minute timeframe. This catalyst, h-BN-Mn, effectively addresses the challenge of elevated manganese leaching rates and exhibits a broad pH degradation spectrum spanning from 3 to 11. Notably, it maintained robust degradation performance over five cycles, showcasing the potential for large-capacity water treatment when integrated with a polyvinylidene fluoride (PVDF) membrane (h-BN-Mn@PVDF), resulting in an 83.8 % removal rate over 6 h. In-depth analysis revealed three distinct degradation pathways. Primarily, the generation of reactive oxygen species (ROS), including singlet oxygen (1O2), played a pivotal role. This was complemented by direct electron transfer from the contaminant to the catalyst-PMS complex, augmented by contributions from Mn(IV) species derived from the complex. This study not only presents a compelling instance of antibiotic degradation through multi-pathway activated PMS but also sheds light on the remarkable synergistic effects achieved by combining manganese oxide with boron and nitrogen compounds.