An Isomer Prediction Model for PCNs, PCDD/Fs, and PCBs from Municipal Waste Incinerators

Abstract

Isomer patterns of polychlorinated naphthalenes (PCNs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated biphenyls (PCBs), and polychlorinated dibenzofurans (PCDFs) from municipal waste incinerators (MWIs) were predicted by a model based on symmetry numbers and preferential chlorination positions. Fly ash isomer patterns from five stoker and seven fluidized bed incinerators were compared to validate the prediction model. The isomer patterns of the highly chlorinated PCN homologues from stoker type incinerators were successfully predicted. The relative equilibrium concentrations of tetrachloronaphthalenes (TeCNs), calculated by an ab initio method, cannot explain the field isomer patterns. Formation pathways involving chlorophenol precursor condensation reactions should be examined to see whether these isomer patterns provide a better fit to the field PCDD data. The PCB isomer patterns were fit reasonably well, but this finding could merely be an artifact of the limited data and the large number of isomers. The prediction equations of PCDFs, revised from prior work to include a symmetry number for each isomer, represented the field data patterns for the higher chlorinated isomers very well. Successful prediction of isomer patterns for partial homologue ranges suggests that these patterns are determined by a mechanism governed by Cl-position-specific preferences.

Polychlorinated naphthalenes (PCNs) in the surface soils of the Pearl River Delta, South China: Distribution, sources, and air-soil exchange

“…4a, while the ff values for CN 51 were extraordinarily higher than the rest of the pentaCNs especially in the summer. CN 51 and 54 are both referred to as "combustion markers" and are associated with many similar thermal processes, e.g., municipal waste incineration (MWI) (Iino et al, 2001;Helm and Bidleman, 2003;Jansson et al, 2008). …”

Estimation of sources and inflow of dioxins and polycyclic aromatic hydrocarbons from the sediment core of Lake Suwa, Japan

“…It is well known that lower levels of chlorinated PCDFs are synthesized in combustion processes (Iino et al, 2001;Rappe et al, 1978;Sakai et al, 1993;Vogg and Stieglitz, 1986;Wilken et al, 1992). The major source of PCDFs in the sediment core from Lake Suwa was considered to be combustion.…”

Role of Hydrogen Abstraction Acetylene Addition Mechanisms in the Formation of Chlorinated Naphthalenes. 2. Kinetic Modeling and the Detailed Mechanism of Ring Closure

“…15−19 This approach has been used to argue for a wide range of routes, such as successive chlorination/dechlorination of PAHs 16,18 or condensation reactions of chlorophenols. 17 These channels may be active for PCN production in municipal waste incinerators (MWIs), 19 shown to be important sources of PCNs in the environment.…”

“…Typically, values greater than 0.7 have been taken to indicate an acceptable level of similarity between two distributions. 16,76 ■ RESULTS AND DISCUSSION A. Experimental Results of Chloroethylene/Trichlorobenzene (Co-)Pyrolyses.…”