Comparative study on naphthalene degradation by Fe(II)-Activated three different oxidants

Abstract

Polycyclic aromatic hydrocarbons (PAHs), exemplified by naphthalene (NaP), are prevalent contaminants in mine tailings wastewater owing to their extensive application as flotation reagents in mineral processing. This study systematically investigated the comparative removal efficiency of NaP via Fe(II)-activated oxidants (sodium persulfate (PS), potassium monopersulfate (PMS), and hydrogen peroxide (H2O2)), under optimized reaction conditions. Among the systems research, the Fe(II)/PS system exhibited superior NaP removal efficiency (98.7 %, kobs = 0.0401 min−1) with minimal pH dependence, whereas Fe(II)/PMS and Fe(II)/H2O2 systems showed significant efficiency reduction at higher pH levels. Reactive oxygen species (ROS) type and relative contribution are the primary limitation for NaP removal. And distinct radical species led to divergent degradation pathways: SO4•--dominated systems (Fe(II)/PS and Fe(II)/PMS) favored hydrogen abstraction, while •OH-dominated Fe(II)/H2O2 proceeded via hydroxyl addition. Common anions (Cl− and HCO3−) inhibited degradation across all systems, albeit to varying degrees. All three systems oxidation processes consistently degraded NaP in both ultrapure water and actual mining wastewater, with Fe(II)/PS achieving 96.9 % removal in mine surface water. Additionally, stepwise Fe(II) addition was shown to significantly enhance PS activation and NaP mineralization. In summary, this study provides theoretical insights for Fe(II)/oxidant applications in PAH-contaminated mining wastewater remediation, recommending Fe(II)/PS as a highly efficient and stable approach for NaP degradation