作　　者： (黄梦瑜）; (彭安萍）; (谷成）;

机构地区： 南京大学环境学院,南京210023

出　　处： 《科学通报》 2017年第24期2709-2716,共8页

摘　　要： 氯代芳香污染物因其对人类健康与生态环境的高威胁性近年来引起了广泛关注,其在土壤中的环境行为成为当前的研究热点.本文系统地介绍了天然蒙脱石黏土矿物在自然环境条件下催化氯代芳香污染物发生聚合的反应机制,该反应以氯代芳香污染物给予蒙脱石层间过渡金属离子一个电子形成阳离子自由基为起始,接着发生一系列聚合反应.蒙脱石特殊的片层微环境能够保护形成的阳离子自由基,从而促进反应的发生.这一反应过程受到多种因素影响,如蒙脱石层间离子类型与存在形态、氯代芳香化合物中氯取代基数量与位置等.然而目前对于这些影响的理论机制还不成体系,需要进一步的深入研究.本文对现阶段关于蒙脱石催化氯代芳香污染物的研究进行归纳与总结,并提出未来可能的研究方向,为今后研究氯代芳香污染物在环境中的迁移转化规律提供新的思路. Chlorinated aromatic pollutants have caused wide concerns in recent years due to its serious threat to human health and the ecological environment, and its environmental behavior in soil has drawn lots of attentions. In addition, some studies showed the presence of dioxin in pristine sites, the congener profiles in these places are different from those in polluted sites, indicating the possible formation of dioxin through natural processes. This current paper reviewed the research progress about the polymerization of chlorinated aromatic pollutants, even forming dioxin, catalyzed by a natural clay mineral, e.g., montmorillonite, under environmentally relevant conditions. Initially, the chlorinated aromatic compound forms a cation-Tz bonding with the transition metal in montmorillonite interlayer. Then, one electron is transferred from chlorinated aromatic pollutant to the transition-metal ion. It results in the formation of the organic radical cation and the reduced transition metal. This organic radical can further react with another neutral molecule or radical to form a series of polymerization products, including dioxins. The unique structure of montmorillonite would promote the reaction by stabilizing the radical cation with its unique planar structure and the negative charge in the interlayer microenvironment. For comparison, the reaction cannot happen if only ferric ion exists. Since montmorillonite is one of the most widely distributed clay minerals, chlorinated aromatic pollutants are also ubiquitous in the environment. Furthermore, the reaction can occur under mild conditions. Therefore, this reaction may provide a possible route for the transport and transformation of chlorinated aromatic pollutants and their derivatives in natural environment. It also provides some evidences for natural formation of dioxin. However, more direct observation and investigation are needed to further study the reaction rate and specific polymerization route for some chlorinated aromatic pollutants. We also need to investig

关 键 词： 天然蒙脱石 氯代芳香污染物 阳离子自由基 过渡金属离子 催化聚合作用