Formation of dioxins from combustion micropollutants over MSWI fly ash.
Formation of polychlorinated dibenzofurans and dibenzo-p-dioxins (PCDD/Fs) from a model mixture of products of incomplete combustion (PICs) representative of municipal solid waste incineration (MSWI) flue gases, over a fixed bed of MSWI fly ash has been investigated. For comparison, a single model compound (chlorobenzene) was also briefly studied. A newly developed lab-scale system enabled the application of (very) low and stable concentrations of organic substances--of 10(-6) M or less-to approach realistic conditions. Samples taken at several time intervals allowed the observation of changes in rates and patterns due to depletion of the carbon in fly ash. The model flue gas continuously produced PCDDs and PCDFs after the de novo reaction had ceased to occur. Dioxin output levels are comparable to those of "old" MSW incinerators. Replacing the PIC trace constituent phenol by its fully 13C-labeled analogue led to, e.g., PCDD with one labeled ring as prominent product, meaning that the formation is about first order in phenol, contrary to earlier assumptions. The meaning of the results for the formation of dioxins in the MSWI boiler is discussed.
Cieplik
Mariusz K
MK
Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
De Jong
Vincent
V
Bozovic
Jelena
J
Liljelind
Per
P
Marklund
Stellan
S
Louw
Robert
R
D000393:Air Pollutants / Q000032:analysis* / Q000737:chemistry; D001572:Benzofurans / Q000032:analysis* / Q000737:chemistry; D002244:Carbon; D002722:Chlorobenzenes / Q000737:chemistry; D060729:Coal Ash; D000072338:Dibenzofurans, Polychlorinated; D006536:Heptanes / Q000737:chemistry; D017745:Incineration; D052638:Particulate Matter; D019800:Phenol / Q000737:chemistry; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry
D000393:Air Pollutants; D001572:Benzofurans; D002722:Chlorobenzenes; D060729:Coal Ash; D000072338:Dibenzofurans, Polychlorinated; D006536:Heptanes; D052638:Particulate Matter; D000072317:Polychlorinated Dibenzodioxins; D019800:Phenol; C028618:n-heptane; D002244:Carbon; C031294:chlorobenzene