Application of sulfidated nano zero-valent iron to enhance fluoranthene degradation by Fe(III) activated sodium percarbonate process in aqueous and soil media

Iron sludge generation poses a challenge to the application of Fenton/Fenton-like processes in wastewater treatment. In this study, sulfidated nano zero-valent iron (S-nZVI) was introduced to enhance the activation of sodium percarbonate (SPC) by Fe(III), mitigating the generation of iron sludge by promoting the Fe(III)/Fe(II) cycle. The proposed technique efficiently removed 94.3% fluoranthene (FLT) in which HO• acted as the major reactive oxygen species responsible for FLT degradation. Toxicity analysis revealed phthalic acid and 1-phenylnaphthalene as FLT degradation intermediates which finally converted to CO2 and H2O. Similarly, the luminous bacteria experiment also showed that the FLT degradation process was environmentally benign. The support of S-nZVI to the Fe(III)/Fe(II) cycle was determined by analyzing the morphology and characterization of S-nZVI. The removal of FLT reached more than 80% at pH ranging from 3.0 to 10.0, and the detrimental effects of low concentrations of Cl− were mitigated. SPC/S-nZVI/Fe(III) process showed good removal of FLT (90%) in both real groundwater and river simulation experiments. Furthermore, SPC/S-nZVI/Fe(III) process was successfully applied in soil slurry media with around 90% FLT degradation in 12 h. The influence of the soil/water ratio on FLT removal was found to be negligible. SPC/S-nZVI/Fe(III) process was superior for the removal of mixed FLT, naphthalene, and phenanthrene contamination. In conclusion, the SPC/S-nZVI/Fe(III) system exhibits enormous potential in the remediation of polycyclic aromatic hydrocarbons (PAHs) contaminated sites.