A review of heterogeneous peroxymonosulfate activation for levofloxacin removal: Bridging pathway analysis and d-band...

Levofloxacin, featured by its complex molecular structure and environmental pseudo-persistence, is widely recognized as a critical emerging micropollutant that demands efficient removal from aquatic environments. Conventional degradation techniques generally suffer from inherent trade-offs. Exhaustive mineralization typically requires high energy input, whereas rapid removal tends to produce transient intermediates with elevated toxicity. This dilemma appears to stem from the intrinsic selectivity of oxidation pathways toward different LEV structural units, which most catalytic systems have limited ability to regulate. Heterogeneous activation of peroxymonosulfate (PMS) has recently attracted attention for its tunable reaction pathways. Guided by d-band theory, this review contrasts radical and non-radical PMS activation mechanisms, and discusses the role of metal d-orbital and non-metal p-orbital hybridization in modulating PMS adsorption and O-O cleavage barriers. Such orbital regulation governs the selectivity among competing activation pathways and establish the catalyst electronic structure-activity relationship. This review also introduces density functional theory (DFT) computational applications in LEV degradation and interprets the ecological hazards of intermediates through toxicity analysis. Prospectively, future research toward high-efficiency, low-toxic LEV degradation should focus on determining the critical threshold for PMS O-O bond dissociation, establishing comprehensive toxicity evaluation criteria, and overcoming the limitation of insufficient mineralization performance.