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 (Fe 3 O 4 ) was investigated. Fe 3 O 4 significantly promoted pyrene removal in the soil; 91.7 % of pyrene was degraded within 45 min treatment. Pyrene removal rate in the Fe 3 O 4 /MW/PS system was 5.18 and 3.00 times higher than that in the Fe 3 O 4 /PS and MW/PS systems. Increasing in Fe 3 O 4 dosage, PS concentration, MW temperature, and soil moisture content in the selected range were conducive for pyrene degradation. SO 4 •− , • OH, O 2 •− , and 1 O 2 were responsible for pyrene degradation, and the conversion of Fe (Ⅱ) in the Fe 3 O 4 to Fe (Ⅲ) contributed to the formation of O 2 •− and 1 O 2 . Characteristic bands of pyrene were more obviously destroyed by the Fe 3 O 4 /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 .