Boron-Accelerated Fe3+/Fe2+ Recycling Enhances Periodate Activation for Sulfamethazine Degradation

Elemental boron, an eco-friendly and cost-effective metalloid reductant, was employed as a reductive co-catalyst to accelerate Fe3+/Fe2+ redox cycling in Fe2+-initiated periodate (PI) activation for sulfamethazine (SMT) degradation. The standalone Fe2+/PI system achieved only 24.1% SMT elimination within 30 min, whereas the constructed B/Fe2+/PI system delivered up to 97.7% removal under an extremely low iron dosage (10 μM Fe2+) and acidic condition (pH 3.0). Radical quenching assays combined with molecular probe identification revealed the co-existence of Fe(IV), •OH, 1O2, O2•−, and IO3•−, with •OH, among which •OH was identified as the dominant oxidant, and its generation was notably amplified by boron. X-ray photoelectron spectroscopy (XPS) characterization demonstrated that surface B-B bonds and low-valent boron moieties act as electron donors to reduce Fe3+ to Fe2+, sustaining continuous Fe3+/Fe2+ redox turnover. Eight transformation intermediates were identified by mass spectrometry, based on which plausible degradation pathways for SMT were proposed. The B/Fe2+/PI system exhibited robust tolerance against prevalent inorganic anions, maintained favorable catalytic capability in natural lake water, and preserved stable performance across five successive recycling runs. Accordingly, boron-augmented Fe2+-triggered periodate activation represents a promising low-iron technical paradigm for antibiotic remediation in water environments.