Identification and characterization of the atmospheric emission of polychlorinated naphthalenes from electric arc furnaces

Abstract

Electric arc furnaces (EAF) are well recognized as significant sources of dioxins. EAFs have also been speculated to be sources of polychlorinated naphthalenes (PCNs) due to the close correlation between dioxin and PCN formation. However, assessment on PCN emissions from EAFs has not been carried out. The primary aim of this preliminary study is to identify and characterize the atmospheric emission of PCNs from EAFs. In this preliminary study, stack gas samples from two typical EAFs with different scales (EAF-1, 160 t batch(-1); and EAF-2, 60 t batch(-1)) were collected by automatic isokinetic sampling technique, and PCN congeners in samples were analyzed by isotope dilution high-resolution gas chromatography combined with high-resolution mass spectrometry method. Emission concentrations of PCNs were 458 and 1,099 ng m(-3) for EAF-1 and EAF-2, respectively. The emission factors of PCNs to air were 21.6 and 30.1 ng toxic equivalent t(-1) for EAF-1 and EAF-2, respectively, which suggested that EAF is an important source of PCN release. With regard to the characteristics of PCNs from EAFs, lower chlorinated homologues were dominant. The PCN congeners comprised of CN27/30, CN52/60, CN66/67, and CN73 were the most abundant congeners for tetra-, penta-, hexa-, and hepta-chlorinated homologues, respectively. EAFs were identified to be an important PCN source, and the obtained data are useful for developing a PCN inventory. The congener profiles of PCNs presented here might provide helpful information for identifying the specific sources of PCNs emitted from EAFs.