Thermochemical Formation of Polybrominated Dibenzo-p-Dioxins and Dibenzofurans Mediated by Secondary Copper Smelter Fly Ash, and Implications for Emission Reduction

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• 作者：Mei Wang ; Guorui Liu ; Xiaoxu Jiang ; Minghui Zheng ; Lili Yang ; Yuyang Zhao ; Rong Jin
• 刊名：Environmental Science & Technology
• 出版年：2016
• 出版时间：July 19, 2016
• 年：2016
• 卷：50
• 期：14
• 页码：7470-7479
• 全文大小：495K
• 年卷期：0
• ISSN：1520-5851

文摘

Heterogeneous reactions mediated by fly ash are important to polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/Fs) formation. However, the formation of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) through heterogeneous reactions is not yet well understood. Experiments were performed to investigate the thermochemical formation of PBDD/Fs at 150–450 °C through heterogeneous reactions on fly ash from a secondary copper smelter. The maximum PBDD/F concentration was 325 times higher than the initial PBDD/F concentration in the fly ash. The PBDD/F concentration after the experiment at 150 °C was five times higher than the initial concentration. PBDD/Fs have not previously been found to form at such a low temperature. Secondary-copper-smelter fly ash clearly promoted PBDD/F formation, and this conclusion was supported by the low activation energies that were found in Arrhenius’s law calculations. Thermochemical formation of PBDD/Fs mediated by fly ash deposited in industrial facilities could explain “memory effects” that have been found for PCDD/Fs and similar compounds released from industrial facilities. Abundant polybrominated diphenyl ethers (PBDEs) that were formed through fly ash-mediated reactions could be important precursors for PBDD/Fs also formed through fly ash-mediated reactions. The amounts of PBDEs that formed through fly ash-mediated reactions suggested that secondary copper smelters could be important sources of reformed PBDEs.