Mechanisms for formation, chlorination, dechlorination and destruction of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)

Pollutant Formation and Emissions from Cement Kiln Stack Using a Solid Recovered Fuel from Municipal Solid Waste

“…The congener profile obtained is typical of environmental samples with a predominance of hepta and octachlorinated congeners, for both dioxins and furans [16].…”

“…Table S1 in the Supporting Information provides the complete data of the analyses done. Profiles shown in Figure 1 are those typical in combustion processes [14][15][16], with a higher amount of furans than dioxins. [ Figure 1] Therefore, it can be concluded that not only the nature of the waste can influence the production of PCDD/Fs, but also the amount of oxygen in the media should be adequate.…”

Formation and potential mechanisms of polychlorinated dibenzo-p-dioxins and dibenzofurans on fly ash from a secondary copper smelting process

“…It has been found in previous studies that copper and zinc are effective in promoting the chlorination pathway for forming PCDD/Fs, and copper and zinc concentrations have been found to positively correlate with PCDD/F concentrations in fly ash (Altarawneh et al 2009;Fujimori et al 2013;Weber et al 2001a, b). Stieglitz et al proposed that surfacebound copper plays a key role in the chlorination reaction and causes the efficient chlorination of carbon substrates, a process that causes the de novo formation of PCDD/Fs (Schwarz and Stieglitz 1992;Stieglitz 1998;Weber et al 2001a, b).…”

“…In a review, Mackie et al stated that sequential chlorination may occur when an excess of chlorine atoms is present and that an abstraction and displacement process will continue until all of the hydrogen atoms on an aromatic ring have been replaced with chlorine, meaning that the most chlorinated PCDD/F homologs will be produced (Altarawneh et al 2009). This was supported by the results of experiments performed by Eiceman et al (Eiceman and Rghei 1982;Rghei and Eiceman 1985a, b).…”

“…This indicates that far more chlorine was present in the original fly ash than present in the PCDD/Fs that were generated, so there would have been an excess of chlorine when the reactions that formed the PCDD/Fs occurred. As mentioned above, the direct chlorination of aromatic compounds, catalyzed by chlorine radicals, can occur when there is an excess of chlorine present, resulting in relatively high concentrations of chlorinated aromatic compounds being formed (Altarawneh et al 2009). As can be seen from Fig.…”