Spontaneous degradation of antibiotics in a heterogeneous Fenton system based on an MoOxSy-decorated iron foam catalytic system

Abstract

The pervasive detection of antibiotics in aqueous environments has garnered significant attention, but effective remediation technologies remain scarce. This work innovatively integrated MoO_xS_y nanostructures directly onto iron foams, providing a highly efficient and reusable catalytic system that overcame iron corrosion and enhanced the radical generation for antibiotic degradation. The composites of MoO_xS_y-decorated iron foam (MIF) were used to activate peroxymonosulfate (PMS) for the degradation of quinolone antibiotics. Remarkably, over 95% of enrofloxacin (ENR) was eliminated within 45 min, achieving a reaction kinetic constant of 0.0813 min⁻¹, which was 3.28-times higher than that of pristine iron foam. Scavenging experiments and electron paramagnetic resonance (EPR) analysis identified ˙O₂⁻ and SO₄˙⁻ as the dominant reactive species responsible for organic compound degradation. Combined experimental and electrochemical investigations confirmed that ENR degradation primarily occurred via a heterogeneous Fenton mechanism. The antibiotic was progressively oxidized into smaller organic intermediates, substantially reducing its cytotoxicity and antibacterial potency. While inorganic salts of NaCl, KCl, and Na₂SO₄ exhibited negligible interferences, Na₂CO₃ and NaNO₃ partially inhibited the degradation process. The catalyst demonstrated excellent reusability, maintaining an ENR removal efficiency exceeding 85% after six cycles. This work offers a promising strategy for addressing antibiotic contamination in aquatic systems.