Pyrene contaminated soil remediation using microwave/magnetite activated persulfate oxidation

Polycyclic aromatic hydrocarbons (PAHs) are important mutagen prevalent in the contaminated sites, bringing potential risks to human health. Iron oxides are important natural components in soils. Pyrene removal in soil using persulfate (PS) oxidation activated by microwave (MW) and magnetite (Fe3O4) was investigated. Fe3O4 significantly promoted pyrene removal in the soil; 91.7 % of pyrene was degraded within 45 min treatment. Pyrene removal rate in the Fe3O4/MW/PS system was 5.18 and 3.00 times higher than that in the Fe3O4/PS and MW/PS systems. Increasing in Fe3O4 dosage, PS concentration, MW temperature, and soil moisture content in the selected range were conducive for pyrene degradation. SO4 center dot-, (OH)-O-center dot, O-2(center dot-), and O-1(2) were responsible for pyrene degradation, and the conversion of Fe (II) in the Fe3O4 to Fe (III) contributed to the formation of O-2(center dot-) and O-1(2). Characteristic bands of pyrene were more obviously destroyed by the Fe3O4/MW/PS oxidation, in comparison with MW/PS oxidation. Ring hydroxylation and ring-opening reactions were the main degradation pathways of pyrene. The toxicities of the formed byproducts were significantly reduced after treatment. This study provided a promising option for pyrene contaminated soil remediation.

Automated summary

The study demonstrated that Fe3O4/MW/PS system significantly increased the removal of pyrene in soil, with a higher degradation efficiency compared to other systems. Increasing Fe3O4 dosage, PS concentration, MW temperature, and soil moisture content contributed to better pyrene degradation.