缓释铁碳复合材料制备优化及其对土壤中多氯联苯（PCBs）的修复机制研究

Remediation of soil contaminated by PCBs (polychlorinated biphenyls) has been one of the important focuses of the soil science. It was well reported that the reductive dechlorination induced by zero-valent iron is an impotant mechanism of PCBs degradation and remediation. However , in the process of remediation of soil by nano-zero-valent iron, problems such as easy agglomeration and difficult diffusion, blocked electron transfer, poor remediation effect appear. Aiming at the above problems, this project puts forward a new idea of repairing soil PCBs by microencapsulated slow-release iron-carbon composite material. First, porous carbon materials loaded with nano-zero-valent iron can effectively avoid the aggregation of nano-zero-valent iron; secondly, the combination of iron and carbon ensures the continuous and efficient electron transfer; and finally, the slow release and enrichment of porous carbon materials, It can change the distribution of pollutants in soil, realize the continuous and effective contact between pollutants and zero-valent iron, and improve the remediation effect under the dual action of adsorption-reduction dechlorination. The feature of the project is to explore the mechanism of PCBs removal in soil remediation by iron-carbon composites and to test the ability of the material to actually reduce and remove PCBs in soil. This work can provide theoretical basis for preparation of supported Iron base composite materials for remediation of PCBs contaminated soils.

多氯联苯（PCBs）是国内外土壤修复的目标化合物之一。现有研究表明，零价铁还原是PCBs的环境降解最佳途径之一，但纳米零价铁在修复过程中会出现易团聚难扩散，电子传递受阻，修复效果差等问题。本项目针对以上问题提出微胶囊缓释铁碳复合材料修复土壤PCBs的新思路。首先，多孔碳材料负载纳米零价铁，可有效的避免纳米零价铁的团聚；其次，铁和碳结合，可确保电子传递的持续有效进行；最后，多孔碳材料的缓释和富集作用，可改变污染物在土壤中的分配，实现污染物与零价铁的持续有效接触，在吸附-还原脱氯的双重作用下，提高修复效果。项目的特色在于探求铁碳复合材料修复土壤PCBs的去除机理，并检验该材料在土壤中实际还原去除PCBs的能力，为基于土壤PCBs污染治理的铁基复合材料制备提供理论支持和技术方法。

针对纳米零价铁在环境修复应用中易团聚、表面易氧化，导致材料电子传递受阻、污染物去除效果降低的现实难题，本项目以提升零价铁的修复效果和探求提升机制为目的，设计并制备了多种兼具提升零价铁分散性及减缓材料氧化的改性铁碳材料（微胶囊缓释铁碳复合材料），实现污染物与零价铁的持续有效接触，并证明微胶囊缓释铁碳复合材料在多种环境条件下可保持长效、高效降解污染物。其次，本项目深入研究了缓释铁碳复合材料对多种污染物的去除效果以及污染物在微胶囊缓释铁碳材料表面的反应动力学和代谢途径。最终建立了以材料优化为基础，污染治理条件探究与机理探究并行的研究方法，为修复材料研发和土壤污染治理提供理论基础和技术支撑，并基于上述成果发表学术论文10篇、申请专利2件、获得省部级奖励2项。