Degradation kinetics, influencing factors, and mechanisms of polycyclic aromatic hydrocarbons in a Fe3O4-nZVI Fenton-like system

To improve the catalytic performance of nano zero-valent iron (nZVI) in a Fenton-like system, Fe 3 O 4 supported nZVI (Fe 3 O 4 -nZVI) was produced by the liquid-phase reduction method and co-precipitation method, then characterized by SEM, EDS, XRD, XPS, and VSM. Fe 3 O 4 -nZVI was used as the catalyst in a Fenton-like system to degrade polycyclic aromatic hydrocarbons (PAHs) such as naphthalene (Nap), phenanthrene (Phe), and pyrene (Pyr) in simulated wastewater. The results showed that under the optimization conditions, which were 25℃, 0.6 g/L of Fe 3 O 4 -nZVI dosage, 3 of the pH in the reaction system, and 10-15 mmol/L of the concentration of H 2 O 2 , the sequence of degradation efficiency in this system was Phe (99.76%)>Pyr (99.71%)>Nap (98.01%). The reused experiments on Fe 3 O 4 -nZVI showed that the degradation efficiency for PAHs remained above 87% after 4 reuses of Fe 3 O 4 -nZVI. These results indicated that nanoscale magnetic composites of Fe 3 O 4 -nZVI had excellent reactivity, stability, and reuse performance. The fitting parameters of kinetics showed that the degradation of PAHs in the Fenton-like system with the Fe 3 O 4 -nZVI catalyst fitted well with the Behnajady-Modirshahla-Ghanbery kinetic model. The radial quenching experiment proved that ·OH was the dominant free radical for the degradation of PAHs in the Fe 3 O 4 -nZVI Fenton-like system. Based on the degradation products of PAHs and the related literature, the possible degradation paths of the three PAHs in the Fe 3 O 4 -nZVI Fenton-like system were inferred. The above results could provide a reference and basis for the treatment of wastewater containing PAHs by Fe 3 O 4 -nZVI Fenton-like technology.