Yuan Songhu, Tian Meng, Lu Xiaohua
Environmental Science Research Institute, Huazhong University of Science and Technology, Wuhan 430074, PR China.
J Hazard Mater. 2006 Sep 21;137(2):878-85. doi: 10.1016/j.jhazmat.2006.03.005. Epub 2006 Aug 8.
This study describes the remediation of hexachlorobenzene (HCB) contaminated soils by microwave (MW) radiation in a sealed vial. When powdered MnO2 was used as MW absorber, a complete removal of HCB was obtained with 10 min MW by the addition of H2SO4 (50%). But no significant decomposition was observed by the addition of NaOH (10 mol/L) or H2O in the same conditions. In contrast, when powdered Fe was used instead of MnO2, the difference of HCB removals between H2SO4 and NaOH were not obvious. It is noteworthy that more than 95% removal was achieved in any case when the sole aqueous solution of H2SO4, NaOH, H2O or Na2SO4 was added without MnO2 or Fe. As a result, it is possible that water itself contained in the damp soil may act as MW absorber and remediate the contaminated soil without addition of any other MW absorbers. Gas chromatograph/mass spectrum (GC/MS) analysis detected no intermediates in all the processes. The decomposition mechanism of HCB by MW radiation was suggested as the binding of HCB and soil. Whatever fragments formed from HCB by heat were tightly bound to the soil, making it impossible to extract them out. In the end, treatment of practical HCB contaminated soil by MW reduced HCB from 55.8 mg/kg to 0.91 mg/kg.
本研究描述了在密封小瓶中通过微波（MW）辐射修复六氯苯（HCB）污染土壤的过程。当使用MnO₂粉末作为微波吸收剂时，加入50%的H₂SO₄并进行10分钟微波辐射可实现HCB的完全去除。但在相同条件下加入10 mol/L的NaOH或H₂O时，未观察到明显的分解现象。相比之下，当使用铁粉代替MnO₂时，H₂SO₄和NaOH处理后HCB去除率的差异并不明显。值得注意的是，在不添加MnO₂或铁粉的情况下，单独添加H₂SO₄、NaOH、H₂O或Na₂SO₄的水溶液时，在任何情况下HCB的去除率都能达到95%以上。因此，潮湿土壤中本身含有的水分可能充当微波吸收剂，在不添加任何其他微波吸收剂的情况下修复受污染土壤。气相色谱/质谱（GC/MS）分析在所有过程中均未检测到中间体。推测HCB通过微波辐射的分解机制是HCB与土壤的结合。HCB受热形成的任何碎片都紧密结合在土壤中，无法将其提取出来。最终，通过微波处理实际受HCB污染的土壤，HCB含量从55.8 mg/kg降至0.91 mg/kg。
