纳米铁负载型活性材料非均匀电极阵列对污染场地中多溴联苯醚和重金属的运移与修复

Nowadays, combined pollution of polybrominated diphenyl ethers(PBDEs) and heavy metals has become a typical form of contaminated sites in China. In the past only remediation of single pollutant was paid attention to, while the remediation of combined pollution of both has never been carried out. It has important application value in developing remediation technology of combined pollution, which is urgently needed. The goal of this project is to develop a high efficient and fast remediation technology on combined pollution. Nano zerovalent iron supported modified active materials (sepiolite, palygorskite, zeolite) are fixed on column electrodes. Pollutants in soil and groundwater are moved to electrodes under weak electric field formed by laying non-uniform electrodes in contaminated sites. Active materials on electrodes capture, transform and degrade pollutants that are removed by replacing electrodes regularly. Simulate and build non-uniform electrode matrix based on characteristics of pollution sites; prove exchange and migration behavior of PBDEs and heavy metals in the soil - groundwater interface; reveal the reaction mechanisms of pollutants on nZVI supported active materials under weak electric field by identifying transformation or degradation products of PBDEs and heavy metals; verify its effects on remediation of practical contaminated sites; theoretical basis and critical technique are provided for the application of the technology.

当前，多溴联苯醚（PBDEs）和重金属复合污染已经成为我国污染场地的一种典型形态。过去，仅仅关注其中单一污染物的修复，而未曾开展二者复合污染的修复研究。开发PBDEs和重金属复合污染修复技术具有迫切需求和重要应用价值。本项目以开发一种高效快速的复合污染修复技术为目标，将负载了纳米零价铁（nZVI）的改性活性材料（海泡石、坡缕石、沸石等）固着在柱状电极上，按非均匀电极阵列布设于污染场地中，施加弱电场将土壤与地下水中的污染物定向运移到电极上，通过活性材料实现对污染物的捕获、转化和降解，定期更换电极实现污染物的去除。模拟构建基于场地污染特征的非均匀电极阵列；探明PBDEs和重金属在土壤-地下水界面间的交换与运移行为；通过鉴定PBDEs和重金属降解、转化产物，揭示在弱电场激活作用下污染物在nZVI负载型活性材料上的反应机理；验证对实际污染场地的修复作用；为该技术的工程应用提供理论依据和关键技术。

针对本项目拟定的研究内容，重点针对nZVI负载材料的制备、表征及其性能，电场作用下土壤中重金属和多溴联苯醚的运移与转化机理开展了深入的研究。研究合成了具有高效反应活性的生物炭-nZVI、海泡石-nZVI、腐殖质-nZVI和坡缕石-nZVI等负载型活性材料，揭示了合成材料实现高效还原重金属和降解PBDEs的内在机理；模拟确定出了优化的非均匀电极阵列；揭示了电场作用下土壤中重金属和PBDEs的迁移规律及重金属的形态转化机制；开展了电场驱动与nZVI可渗透反应墙结合去除土壤中PBDEs的实验，探索了该套反应系统中的PBDEs的运移与降解规律；首次比较系统地揭示了不锈钢电极应用于电动修复重金属污染土壤过程中电极腐蚀与结晶现象及其机制，探索了电动修复中不锈钢电极的缓蚀与阻垢方法；揭示了PASP与CA在该过程中的脱毒效应及其机制，并首次比较系统地揭示了电动修复重金属污染土壤中的热效应现象及其能量分配机制；制备了nZVI负载型活性材料电极，并使用该电极开展了现场修复试验。上述成果对推动该技术的发展起到了重要影响和积极作用。截至目前，已在SCI及EI收录期刊上共发表论文11篇，申请发明专利3项，超额完成了预定考核指标