模拟飞灰催化芴生成二噁英试验研究

Experimental study of PCDDs/Fs formation from fluorene catalyzed by model fly ash

为了找出多环芳烃生成二噁英的反应途径,选取了多环芳烃中具有代表性、和二噁英结构比较类似的芴作为多环芳烃的模型化合物,以氯化铜和石英砂作为模拟飞灰的基本成分,比较添加氯化铁、氧化铜或者在气氛中添加氯气对二噁英生成的作用.结果显示,模拟飞灰氧化性的增强使反应向从头合成反应机制的方向移动,氯化性的增强使反应向前驱物反应机制反应方向移动.无论是模拟飞灰氧化性的增强或者氯化性的增强,生成的二噁英的毒性当量都有所增加,但是后者的作用更为显著.芴在模拟飞灰催化生成二噁英的反应是从头合成反应机制和前驱物反应机制综合作用的结果.

Experiments were conducted to investigate the formation of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans （PCDDs/Fs） from polycyclic aromatic hydrocarbons （PAHs） catalyzed by model fly ash. The typical PAHs, fluorine was taken as reaction material based on its similar chemical structure with PCDDs/Fs, and quartz sand mechanically mixed with copper chloride as model fly ash （MFA） . The effects of copper chloride, ferric chloride, copper oxide and chlorine on PCDDs/Fs formation were compared. Results indicated that reaction moved according to de novo synthesis mechanism with the increase of oxidation ability of MFA, while increasing chlorinating ability moved reaction towards precursor formation mechanism. Higher oxidation and chlorinating ability of MFA resulted in increasing toxicity equivalence quantity （TEQ） of PCDDs/Fs , and the effect of chlorinating ability was more evident. Formation of PCDDs/Fs from fluorine catalyzed by MFA was the combined results of de novo synthesis mechanism and precursor compounds mechanism.