Norfloxacin degradation by rare-earth cerium-doped cobalt catalysts via PMS Activation: performance evaluation and mechanism insights

Peroxymonosulfate (PMS)-based advanced oxidation processes have gained significant attention due to their strong oxidative capacity and rapid reaction kinetics. However, the development of efficient, stable, and eco-friendly catalysts remains a major challenge in realizing practical applications. To address this issue, a novel catalyst, Co 1 Ce 2 O x @PAL, was synthesized via the sol-gel method to enhance PMS activation efficiency by leveraging rare-earth doping and the carrier properties of palygorskite (PAL). Comprehensive characterization (SEM, XRD, FTIR, etc.) confirmed successful synthesis and favorable structural properties. Norfloxacin (NOR) was selected as the target contaminant to evaluate the catalytic performance of Co 1 Ce 2 O x @PAL. Under an optimal condition (30% metal loading, 0.3 g/L catalyst, 0.5 mM PMS, pH 6.2), NOR removal efficiency reached 95%, with an apparent rate constant of 0.15 min -1 . Quenching tests and electron paramagnetic resonance (EPR) analyses revealed that played a dominant role in NOR degradation. and were generated through the redox reactions between Co 2+ /Co 3+ and Ce 3+ /Ce 4+ . Furthermore, oxygen vacancies facilitated electron transfer, thereby promoting radical production and NOR degradation efficiency. DFT calculation, including electrostatic potential and frontier orbital analyses (HOMO/LUMO), identified the quinolone and piperazine rings as the most susceptible sites for radical attack. Four potential degradation pathways were proposed accordingly. The catalyst demonstrated a high stability and reusability, maintaining over 80% NOR removal after five cycles. ECOSAR predicted reduced toxicity for most transformation products. This study highlights the potential of Co 1 Ce 2 O x @PAL as an effective catalyst for sustainable water treatment by enabling efficient degradation of trace emerging contaminants and promoting water resource recycling.