College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, PR China.
College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, PR China.
J Hazard Mater. 2018 Sep 15;358:265-272. doi: 10.1016/j.jhazmat.2018.06.056. Epub 2018 Jun 25.
In the present study, biodegradable ligand EDDS was employed to assist ZVI on simultaneous remediation of PCB and heavy metals co-contaminated soils under aerobic condition. With addition of 4 mmol L EDDS and 5 g L ZVI, the total removal ratio of PCB reached 75.3%, and the stabilization ratio of Pb and Cu attained 97.1% and 91.9% respectively. EDDS played two key roles during the process. Firstly, the addition of EDDS could enhance hydroxyl radical generation by ZVI and oxygen for the oxidation of PCB including distribution in the soil phase and dissolved form in the aqueous phase. Secondly, free EDDS could accelerate the release of Cu and Pb from the soil phase to the aqueous phase. As the oxidation of EDDS and the increase of pH value during the process, the dissolved Cu and Pb could be efficiently stabilized by iron oxyhydroxide through coprecipitation. Compared with ZVI/Air, ZVI/EDDS/Air treatment could significantly enhance the stabilization of Pb and Cu. The reason was the dissolution of Cu and Pb by EDDS extraction could reduce the mass transfer limitations between heavy metals and iron oxyhydroxide. Therefore, our study suggests a promising alternative for remediation of organic compounds and heavy metals co-contaminated soil.
在本研究中，采用可生物降解的配体 EDDS 来协助 ZVI 在有氧条件下同时修复 PCB 和重金属复合污染土壤。添加 4 mmol L EDDS 和 5 g L ZVI 后，PCB 的总去除率达到 75.3%，Pb 和 Cu 的稳定化率分别达到 97.1%和 91.9%。EDDS 在整个过程中发挥了两个关键作用。首先，EDDS 的添加可以增强 ZVI 和氧气产生的羟基自由基，从而氧化 PCB，包括在土壤相和水相溶解形式中的分布。其次，游离 EDDS 可以加速土壤相中 Cu 和 Pb 的释放到水相。由于 EDDS 的氧化和过程中 pH 值的增加，溶解的 Cu 和 Pb 可以通过共沉淀被铁氧氢氧化物有效地稳定。与 ZVI/Air 相比，ZVI/EDDS/Air 处理可以显著增强 Pb 和 Cu 的稳定化。原因是 EDDS 提取的 Cu 和 Pb 的溶解可以减少重金属和铁氧氢氧化物之间的传质限制。因此，我们的研究为有机化合物和重金属复合污染土壤的修复提供了一种很有前景的替代方法。
