Mixed-phase FeMoO4 for synergistic photocatalytic peroxydisulfate activation toward efficient tetracycline degradation

Abstract

Tetracycline (TC), a broad-spectrum antibiotic, poses a significant threat as an aquatic pollutant due to its persistence and role in promoting antibiotic resistance. Advanced oxidation processes, particularly persulfate-based photocatalytic oxidation, are promising for TC removal. This study investigates mixed-phase iron(II) molybdate (FeMoO₄) as a visible-lightresponsive photocatalyst for activating peroxydisulfate (PDS) to degrade TC. Hydrothermally synthesized FeMoO₄ exhibited a mixed-phase structure with high crystallinity. Under visible light and optimized conditions, the mixed-phase FeMoO₄/PDS system achieved 94.18% TC removal within 40 minutes. Quenching experiments and electron paramagnetic resonance identified sulfate radicals (SO₄•⁻) as the primary active species. The degradation pathway involved deamination, hydroxylation, and ring-opening, leading to mineralization. The material maintained 90.60% efficiency after four cycles, demonstrating high stability. Mixed-phase FeMoO₄ is thus an effective and durable catalyst for synergistic persulfateassisted photodegradation of antibiotics.