A preliminary investigation on emission of polychlorinated dibenzo-p-dioxins/dibenzofurans and dioxin-like polychlorinated biphenyls from coke plants in China

Thermal related processes are widely recognized as the main sources of formation and emission of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs). It is well known that, carbonization of coal in coke production involves many thermal reactions at high-temperature. However, there are still no strong evidences to identify coking processes as source of PCDD/Fs and PCBs. In this study, coke production was qualified and quantified for emission of PCDD/Fs and dioxin-like PCBs (dl-PCBs) in some typical coke plants in China. In the preliminary investigation, stack gases from three typical coke plants were collected, and dl-PCBs and 2378-substituted PCDD/Fs were analyzed by isotope dilution HRGC/HRMS technique. The total toxic equivalents of dl-PCBs and PCDD/Fs were in the range of 1.6-1785.4 pg WHC-TEQ Nm(-3). For dl-PCBs, the most abundant congener was CB-118, and the most dominant contributor to total WHO-TEQ of dl-PCBs was CB-126. With regard to PCDD/Fs, four congeners comprised of OCDD, 1234678-HpCDD, 1234678-HpCDF and OCDF were the predominant species in stack gases. Further investigation on the emission of dioxins from coking industry is still in process. (C) 2009 Elsevier Ltd. All rights reserved.