氧化铁矿物在微波修复多环芳烃污染土壤中的作用机制

The Mechanism of Iron Oxide Minerals in the Microwave Remediation of Soil Contaminated by Polycyclic Aromatic Hydrocarbons

多环芳烃(PAHs)是焦化污染场地中常见的污染物.微波修复具有加热均匀、能耗低、耗时短的特点,在土壤修复中有较好的应用前景.该研究选择氧化铁矿物含量低的污染土壤作为试验对象,分别添加10%的针铁矿、赤铁矿和磁铁矿,对添加前后土壤的吸波性能、升温特性及PAHs去除率进行研究,评价氧化铁矿物在微波修复PAHs污染土壤中的作用.结果表明:土壤中加入氧化铁矿物能够改善其吸波性能,提高复介电常数、复磁导率的实部值和复磁导率的虚部值,最大增幅分别为31.79%、12.24%和73.91%.氧化铁矿物的加入使得土壤产生自由基,促进土壤极化现象,增强吸波能力.氧化铁矿物还能够改善土壤的升温特性,当微波功率为600 W时,添加了针铁矿、赤铁矿、磁铁矿的土壤所达到的最高温度分别是原土壤的1.23、1.10和1.07倍.随着温度的升高,PAHs去除率随之升高,分别是原土壤的1.45、1.31和1.48倍.研究显示,氧化铁矿物的添加能够提高微波修复PAHs的效能.

Polycyclic aromatic hydrocarbons(PAHs) are common pollutants in coke-contaminated sites. Microwave remediation has been widely applied in soil remediation due to its uniform heating of materials, low energy consumption, and short remediation time. In this study, the effect of iron oxide minerals on the microwave remediation of soil contaminated by polycyclic aromatic hydrocarbons is evaluated. The contaminated soil with low iron oxide content was selected as the object, 10% goethite, hematite and magnetite were added,and then the microwave remediation was conducted. The absorption ability, heating characteristics and removal rate of PAHs in the absence or presence of iron oxide were observed. The results showed that the addition of iron oxide minerals to the soils improved the adsorption property. The real complex permittivity, permeability, and imaginary permeability were increased by 31.79%, 12.24% and73.91%, respectively. The addition of iron oxide minerals led to the increase of free radicals in the soils and facilitates the polarization of soil, which can enhance the absorption capacity. Iron oxide also improved the soil heating characteristics. When the microwave power was600 W, the maximum temperature of the soil with goethite, hematite and magnetite was 1.23, 1.10 and 1.07 times 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 that of the original soil,respectively. The results showed that the addition of iron oxide minerals could improve the efficiency of microwave remediation of PAHs.