工业热过程中过渡金属化合物对卤代多环芳烃生成和转化的作用机理研究

工业热过程非故意排放是新型持久性有机污染物XPAHs的主要污染来源。热过程中XPAHs的生成机制具有特异性，但相关研究尚未系统开展。前期研究发现过渡金属化合物会参与XPAHs的异相生成反应。为了探索热过程XPAHs的生成机理以及其中过渡金属化合物的作用机制，本项目拟从以下几方面展开研究：首先基于再生金属冶炼过程飞灰样品，筛查并识别XPAHs前驱体；配置不同过渡金属化合物和前驱体物质组成的模拟飞灰样品，模拟不同机制作用下生成XPAHs的过程，结合量子化学理论计算结果，明确XPAHs的生成途经和影响因素；采用原位加热技术，利用电子顺磁共振波谱仪检测XPAHs生成过程自由基的种类、含量等特性，阐明该过程自由基中间体的生成和转化途径以及过渡金属化合物的作用机制。研究结果将揭示热过程中XPAHs的生成机制和影响因素，为从源头控制XPAHs，探索其减排和阻滞技术提供重要理论支持。

Chlorinated and brominated polycyclic aromatic hydrocarbons (XPAHs) are new persistent organic pollutants. Unintentional emissions from various industrial thermal processes are major sources of XPAHs. In these thermal processes, formation mechanisms of XPAHs are different from other POPs, but researches on formation mechanisms of XPAHs have not been systematically conducted yet. In our previous studies, we found that the transition metal compounds would participate in the heterogeneous formation reactions of XPAHs. In order to explore formation mechanisms of XPAHs and roles of transition metal compounds in thermal processes, we therefore plan to conduct this study as follows: First of all, with the collected fly ash samples from secondary metallurgical smelting processes, we will screen and quantify the XPAH precursors. Based on these results, we will configure the simulated fly ashes which consist of different transition metal compounds and XPAH precursors. We will then simulate the formation processes of XPAHs in the laboratory under different formation mechanisms. Combined with the calculation results of quantum chemistry theory, the formation pathways and influencing factors will then be clarified. Besides that, we will use the in-situ heating technique and electron paramagnetic resonance spectrometer to analyze the characteristics, such as types and levels, of free radicals during these XPAH formation processes, and elucidate the formation and transformation of free radical intermediates and roles of transition metal compounds. Results of this study would reveal the mechanisms and influencing factors for XPAH formation during thermal processes, so that provide theoretical support for controlling XPAHs from sources and exploring its emission reduction technologies.