Dual-Pathway Peroxymonosulfate Activation on FeNi-CNT@Al₂O₃ for Efficient Tetracycline Hydrochloride Degradation

Transition metal alloy catalysts are promising for advanced oxidation processes, but their application is often limited by insufficient interfacial electron transfer and poor stability. Herein, we engineered a robust FeNi-CNT@Al₂O₃ catalyst, derived from waste aluminum ash, for the activation of peroxymonosulfate (PMS) and tetracycline hydrochloride (TCH) degradation. The catalyst features nitrogen-doped carbon nanotubes (CNTs) with encapsulated Fe-Ni alloy nanoparticles grown on an alumina-rich carbon matrix, creating an efficient interfacial catalytic platform through the synergy between CNT-mediated electron transfer and Fe-Ni-enhanced redox cycling. The optimized Fe₁Ni₂-CNT@Al₂O₃/PMS system achieved 100% TCH degradation with 73.5% chemical oxygen demand (COD) and 69.3% total organic carbon (TOC) removal within 30 min. Mechanistic investigations revealed that the degradation is dominated by a non-radical ¹O₂ pathway, with radical species ( and ) and direct electron transfer as secondary contributors. Density functional theory calculations further elucidated the critical role of Fe-Ni alloy loading in enhancing interfacial PMS adsorption and charge transfer. Notably, the catalyst maintained 91.8% TCH removal after 100 h of continuous operation. This work provides a sustainable strategy for upcycling solid waste into high-performance catalysts and elucidates the mechanism of ¹O₂-dominated PMS activation for persistent organic pollutant remediation.