Fe3o4-Ce@Bc Activates Persulfate for the Degradation of Polycyclic Aromatic Hydrocarbons (Pahs) in Contaminated Soil

Polycyclic aromatic hydrocarbons (PAHs) contaminated sites must be restored to below the controlled value before reused due to their mutagenic, carcinogenic, and teratogenic effects. Advanced oxidation processes (AOPs) based on persulfate not only simple operation low cost but also can dissolve into S2O82- to produce SO4·-, which has the high redox potential, on this account, it has attracted wide interest for the treatment of aromatic compounds. In this work, Fe3O4-Ce@BC composite material was synthesized by the hydrothermal co-precipitation method and used to activate persulfate (PS) for the removal of PAHs in soil. The results indicated that the total PAHs removal rate reached 89.34% when the dosage of PS was 0.5 mmol/g, the dosage of activator was 40 mg/g, the liquid and soil ratio was 5:1, the initial optimum pH was 5, the degradation rates of Naphthalene (Nap), Phenanthrene (Phe), Pyrene (Pyr) and Benzo (a) pyrene (BaP) were 83.58%, 74.28%, 95.97%, and 99.19%, respectively. Also, the degradation of PAHs achieved an optimistic result in a wide pH range. The degradation mechanism of PHAs was also investigated by EPR and free radical masking tests simultaneously，although it did not clarify which plays a dominant role, it proved that the degradation of PAHs in the Fe3O4-Ce@BC/PS system was achieved by SO4·−, ·OH, O2·−, 1O2 and electron transport processes. The results of the change of dissolved organic carbon (DOC) and soil organic matter (SOM) after remediation have shown that a large amount of organic matter was released, DOC content increased, SOM decreased after the soil remediation test. The results raised a novel preparation method, which provided a new idea for the future research and preparation of biochar.