Mechanism of Formation of Chlorinated Pyrene during Combustion of Polyvinyl Chloride

Chlorinated polycyclic aromatic hydrocarbons (ClPAHs) are an emerging class of environmental contaminants, but the sources of these chemicals in the environment are not well-known. In this study, we developed a kinetic model describing the chlorination of PAHs to elucidate the mechanism of formation of ClPAHs during the combustion of organic waste containing chlorinated compounds and/or chlorine in an incinerator. Pyrene (Pyr) and polyvinyl chloride (PVC) were selected as a model PAH and a model organic substrate, respectively. All combustion experiments were carried out using a model furnace operated under similar experimental conditions. Combustion of PVC in the model furnace produced 1-ClPyr, 1,3-Cl₂Pyr, 1,6-Cl₂Pyr, 1,8-Cl₂Pyr, 1,3,6-Cl₃Pyr, and 1,3,6,8-Cl₄Pyr. The developed model supported the experimental data on the sequential chlorination of pyrene. The rate constants for the formation of mono- to trichlorinated pyrenes were over 30 times of those for the formation of tetra- and penta-chlorinated pyrenes. A qualitative analysis of the formation of highly chlorinated pyrenes based on the comparison of theoretical and empirical isotopic patterns of the mass spectrum revealed that penta- and hexa-chlorinated pyrenes, whose analytical standards were not available, were also produced by the combustion of PVC.