Abstract:
Polycyclic aromatic hydrocarbons (PAHs) are the common pollutants in coke pollution sites. Microwave remediation has been widely applied in soil remediation because it has characteristics of homogeneous heating of substance, low energy consumption jointly with short remediation times. In this study, the effect of iron oxide minerals on the microwave remediation of soil contaminated by polycyclic aromatic hydrocarons is evaluated. The contaminated soil with low iron oxide content was selected as the object, and goethite, hematite and magnetite with 10%wt were added, after which the microwave remediation was conducted. The absorbing ability, heating characteristics and removal rate of PAHs in the absence or presence of iron oxide were observed. The results show that the addition of iron oxide mineral in soils can improve the adsorption property. The values of the real complex permittivity and permeability as well as the imaginary permeability are increased by 31.79%、12.24% and 73.91%, respectively. The addition of iron oxide minerals leads to more free radicals in soils and facilitates the polarization of soil, which can enhance the ability of absorption. Iron oxide can also improve the soil heating characteristics. When the microwave power was 600W, the maximum temperature of the soil with goethite, hematite and magnetite added was 1.23, 1.10 and 1.07 times more than that of the original soil, respectively. With the increase of temperature, the removal rates of PAHS were 1.45、1.31 and 1.48 times more than that of the original soil, respectively. The results showed that the addition of iron oxide mineral could improve the efficiency of PAHs microwave remediation.