工业热过程中无意产生的持久性有机污染物生成机理

Formation mechanism of unintentionally produced persistent organic pollutants in industrial thermal processes

持久性有机污染物(persistent organic pollutants, POPs)可在工业热过程中无意生成和被排放,而探究其生成机理是发展源头减排技术的基础.本文在梳理文献的基础上,发现二英的生成理论有了一些新的突破.关于氯酚和氯苯等前驱体在热过程中生成自由基中间体的研究,能够从分子层面上揭示二英的生成机制,丰富了POPs的生成理论体系.同时发现,碳源、氯源和催化金属的类别及含量是影响焚烧或冶金等工业热过程中典型无意POPs产生和排放的关键因素.本文也重点总结了过渡金属氯化物在POPs生成反应中起的关键作用,发现其既可作为反应的催化剂,也可作为无机氯源促使大分子碳结构的有机物发生氯化反应,经氧氯化循环促进POPs的生成.该文可为POPs的源头控制技术开发提供理论参考.

Persistent organic pollutants(POPs) can be unintentionally produced and emitted in industrial thermal processes. The investigation of their formation mechanism is the basis for the development of source reduction technologies. In this paper, we found some new breakthroughs in the theory of dioxin formation on the basis of literature. The research on the formation of free radical intermediates from precursors such as chlorophenols and chlorobenzenes in thermal processes can reveal the formation mechanism of dioxin at the molecular level, which enriches the theoretical system of POPs formation. It is also found that the type and content of carbon sources, chlorine sources and catalytic metals are the key factors influencing the generation and emission of typical unintentional POPs in industrial thermal processes such as incineration and metallurgy. This paper also highlights the key role of transition metal chlorides in the generation of POPs, which can serve as not only a catalyst for the reaction, but also an inorganic chlorine source to chlorinate organic compounds with macromolecular carbon structures, thus promoting the formation of POPs. This review can provide important theoretical basis for the source control of POPs.