高锰酸钾修复PAHs污染土壤过程中Mn迁移转化规律

为探究高锰酸钾氧化修复技术应用过程中Mn元素迁移转化规律及其潜在的环境风险，通过室内模拟实验，采用某焦化厂PAHs污染土壤作为研究材料，探究了高锰酸钾修复技术中不同药剂投加量对PAHs去除、高锰酸钾消耗量、土壤中Mn质量分数、Mn赋存形态分布及有效态Mn质量分数等的影响。结果表明，高锰酸钾氧化处理可有效去除土壤中PAHs；当高锰酸钾投加量为0.20 mmol·g⁻¹、反应时间为1 d时，PAHs去除率最高，可达89.61%。氧化处理过程中，高锰酸钾消耗量和土壤Mn质量分数均与高锰酸钾的投加量有关，随投加量增加而升高。其中，土壤Mn的质量分数与高锰酸钾消耗量呈显著正相关关系。高锰酸钾氧化处理后土壤中Mn主要以铁锰氧化物结合态存在，所占比例为77.04%~92.17%。土壤经0.05 mmol·g⁻¹高锰酸钾氧化处理后，土壤有效态Mn的质量分数比对照组增加了0.94倍；而在高锰酸钾投加量为0.10~0.40 mmol·g⁻¹的处理条件下，土壤有效态Mn的质量分数下降了77.65%~99.09%。药剂投加量是影响高锰酸钾氧化修复PAHs污染土壤过程中Mn环境行为的关键因子。本研究结果可为高锰酸钾氧化修复技术应用工艺优化提供参考。

Migration and transformation of Mn during remediation process of soil contaminated with PAHs by potassium permanganate oxidation

Potassium permanganate oxidation is an effective soil remediation technology being used widely for removing PAHs from soil. In order to investigate the migration and transformation of Mn, and its potential environmental risk during remediation process of soil contaminated with PAHs by potassium permanganate oxidation, a simulation experiment was carried out with PAHs contaminated soil from a coking site. The effects of different doses of potassium permanganate on amount of consumed potassium permanganate, content of manganese (Mn), speciation of Mn and extractable Mn content in soil were investigated. Then, the migration and transformation of Mn during the remediation process of PAHs contaminated soil by potassium permanganate oxidation was explored. The results showed that potassium permanganate may effectively remove PAHs from the soil of the coking plant. When the dosage of potassium permanganate was 0.20 mmol·g−1 and the reaction time was 1 d, the removal rate of PAHs was the highest, reaching 89.61%. In the remediation process, potassium permanganate consumption and contents of Mn in soil increased with the dose level of potassium permanganate. The result of correlation analysis demonstrated that there is a significant positive correlation between the content of Mn in soil and the amount of consumed potassium permanganate. Moreover, Mn in soil existed mainly in Fe-Mn oxides bound fraction, and its proportions were 77.04%~92.17%. Compared to the treatment without potassium permanganate, the content of extractable Mn in soil increased by 0.94 times after treatment with potassium permanganate at 0.05 mmol·g−1. However, extractable Mn content in soil declined by 77.65% to 99.09% after treatment with potassium permanganate oxidation at 0.10~0.40 mmol·g−1. In conclusion, the dose of oxidant is a key factor for the environmental behaviors of Mn in soil during the remediation process of PAHs contaminated soil by potassium permanganate oxidation. The results of this study can provide a reference for the process optimization of application of potassium permanganate oxidation.