Hydroxylamine enhanced FeOOH-mediated advanced oxidation processes for the treatment of norfloxacin

In recent years, advanced oxidation processes (AOPs) based on persulfate (PDS) and hydrogen peroxide (H₂O₂) have become widely used for removing antibiotics from water. However, the formation of iron sludge limits the practical application of homogeneous iron-based catalysts for activating H₂O₂ and PDS. Therefore, heterogeneous catalysis offers a promising alternative. This study compares the degradation of norfloxacin (NOR) using FeOOH-activated PDS and H₂O₂ in a photocatalytic system. Hydroxylamine (HA) was employed to assist the activation process to further optimize the degradation process and improve the degradation efficiency. Without the presence of HA, the findings revealed that the degradation rates of NOR were merely 31.2% in the PDS system and 24.8% in the H₂O₂ system. The introduction of HA markedly improved NOR degradation efficiency, achieving removal rates of 89.7% in the PDS system and 56.3% in the H₂O₂ system. Key operational parameters including pH, HA concentration, oxidant dosage, and the presence of HA were systematically evaluated for their influence on degradation performance. Scavenging experiments revealed that ⋅OH, SO₄⁻⋅, and ⋅O₂⁻ served as the dominant reactive species in the PDS system, whereas h⁺ and ⋅OH were the primary drivers in the H₂O₂ system. Based on these findings, a plausible reaction mechanism was proposed. Additionally, the stability of the FeOOH catalyst in the presence of HA and its effectiveness in degrading NOR across various water matrices were investigated. This study offers an innovative strategy for visible-light-assisted activation of H₂O₂ and PDS, demonstrating considerable potential for antibiotic degradation in water treatment applications.