Nganai Shadrack, Lomnicki Slawo
Chemistry Department, South Louisiana Community College, Lafayette, LA, USA.
Department of Environmental Sciences, Louisiana State University, Baton Rouge, LA, USA.
Int J Environ Pollut. 2017;61(3-4):208-222. doi: 10.1504/IJEP.2017.10008687.
We report results on PCDD/F formation over iron (III) oxides catalysts for a mixture of 2-monochlorophenol (2-MCP) and 1,2-dichlorobenzene (1,2-DCBz) for both oxidation and pyrolysis. Competitive adsorption between chlorinated benzenes and chlorinated phenols affects the transformation of these precursors and plays a crucial role in the PCDD/F formation in mixed MCP/1,2-DCBz-feed streams. Comparing the integrated PCDD and PCDF yields, it becomes apparent that with decreasing 2-MCP content in the feed stream the PCDF yield first rises and then levels off, at ~0.4% for pyrolytic and at ~0.6% for oxidative conditions. Present results further confirm that the PCDD/PCDF-ratio cannot be used to validate the de novo pathway nor can it be used as an indicator of de novo synthesis in incinerators. In fact, the PCDD/PCDF-ratio is strongly dependent on the relative concentration of these two precursors in the reacting stream, i.e., chlorinated benzenes vs. chlorinated phenols.
我们报告了在铁（III）氧化物催化剂上，2-一氯苯酚（2-MCP）和1,2-二氯苯（1,2-DCBz）混合物在氧化和热解过程中多氯二苯并二恶英/多氯二苯并呋喃（PCDD/F）形成的结果。氯苯和氯酚之间的竞争吸附影响这些前体的转化，并在混合MCP/1,2-DCBz进料流中PCDD/F的形成中起关键作用。比较PCDD和PCDF的综合产率，很明显，随着进料流中2-MCP含量的降低，PCDF产率先上升然后趋于平稳，热解条件下约为0.4%，氧化条件下约为0.6%。目前的结果进一步证实，PCDD/PCDF比值不能用于验证从头合成途径，也不能用作焚烧炉中从头合成的指标。事实上，PCDD/PCDF比值强烈依赖于反应流中这两种前体的相对浓度，即氯苯与氯酚的相对浓度。
