Fluoranthene degradation in a persulfate system activated by sulfidated nano zero-valent iron (S-nZVI): performance and mechanisms

Abstract

Fluoranthene (FLT) has received mounting focus due to its hazardous properties and frequent occurrence in groundwater. In this study, sulfidated nano zero-valent iron (S-nZVI) was selected as an efficient catalyst for activating persulfate (PS) to degrade FLT. The effects of reagent doses, various water conditions (pH, anions, and humic acid), and the presence of surfactants on FLT degradation were investigated. Radical probe experiments, electron paramagnetic resonance (EPR) spectrum detection, and scavenging tests were performed to identify the major reactive oxygen species (ROS) in the system. The results showed that in the PS/S-nZVI system, 96.2% of FLT was removed within 120 min at the optimal dose of PS = 0.07 mM and S-nZVI = 0.0072 g L−1. S(-II) in the S-nZVI surface layer promoted Fe(II) regeneration. Furthermore, HO• and SO4−• were identified as the main contributors to FLT degradation. The intermediates of FLT degradation were detected by gas chromatograph-mass spectrometry (GC-MS) and a possible FLT degradation pathway was proposed. Finally, the effective degradation of two other common polycyclic aromatic hydrocarbons (PAHs) (naphthalene and phenanthrene) demonstrated the broad-spectrum reactivity of the PS/S-nZVI process. In conclusion, these findings strongly demonstrate that the PS/S-nZVI process is a promising alternative for the remediation of PAH-contaminated groundwater. HIGHLIGHTS HO• and SO4−• were the primary ROS in the PS/S-nZVI system for FLT degradation.; The possible degradation pathway of FLT was proposed.; The S(-II) enhancement mechanism was fully described.; Efficient FLT degradation in actual groundwater was achieved.; The broad-spectrum reactivity of the PS/S-nZVI system was investigated for other PAHs removal.;

Keywords

• fluoranthene
• groundwater remediation
• persulfate
• polycyclic aromatic hydrocarbons
• sulfidated nano zero-valent iron