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

Abstract

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.

Effects of Desulfurization Processes on Polybrominated Dibenzo-p-dioxin and Dibenzofuran Emissions from Iron Ore Sintering

“…The PBDD/F concentrations in the fly ash samples from each ESP stage in small IOSPs were higher than the corresponding concentrations in the medium and large IOSPs. The PBDD/F concentrations were higher in the sintering fly ash sample from the last ESP stage than those reported in the fly ash from secondary copper smelting …”

“…The PBDD/F congeners of interest were identified and quantified by isotope-dilution high-resolution gas chromatography combined with high-resolution mass spectrometry. The analytical technique and the methods used are described in detail elsewhere. ,, Briefly, each stack gas sample was spiked with a known amount of 13 C 12 -labeled PBDD/F internal standard (EDF-5408; Cambridge Isotope Laboratories, Andover, MA, U.S.A.) and then Soxhlet extracted with 250 mL of toluene for approximately 24 h. Before extraction, the fly ash and desulfurization product samples were digested in hydrochloric acid. Each extract was evaporated to yield a small volume using a rotary evaporator.…”

Profiles, sources and potential exposures of parent, chlorinated and brominated polycyclic aromatic hydrocarbons in haze associated atmosphere

“…As regards to BrPAHs, even less studies have reported their profiles in the atmosphere. In previous studies, sources that emitted chlorine-substituted POPs also emitted their brominate-substituted analogs (Li et al, 2015;Wang et al, 2016). Therefore, the sources that emitted ClPAHs could also be regard as potential sources of BrPAHs.…”

Secondary Copper Smelters as Sources of Chlorinated and Brominated Polycyclic Aromatic Hydrocarbons

“…The formation of brominated POPs seem to go through similar pathways as their chlorinated analogs. 40 Correlations…”