Formation and contamination of PCDD/Fs, PCBs, PeCBz, HxCBz and polychlorophenols in the production of 2,4-D products

摘要

The concentrations and profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), poly-chlorinated biphenyls (PCBs), pentachlorobenzene (PeCBz), hexachlorobenzene (HxCBz) and polychlorophenols in 2,4-D were investigated in this study. Two 2,4-D acid and three 2,4-D butyl ester enterprises were selected as typical 2,4-D producers. The total concentrations of 2,3,7,8-PCDD/Fs in the 2,4-D samples ranged from 355 to 35080 ngkg~(-1) and the corresponding TEQ values were in the range of 13.4 and 694.6 ng WHO-TEQkg~(-1). The concentrations of total PCBs in the 2,4-D were in the range of 16.1 and 8023 ng kg~(-1), and the WHO-TEQ values of the PCBs were between 0.057 and 108.3 ng WHO-TEQkg~(-1), while total PCBs were between 1486 and 47342 ng kg~(-1). The average emission factors were 414.4 μg WHO-TEQ t~(-1) for PCDD/Fs and 21.9 μg WHO-TEQ t~(-1) for PCBs. The polychlorobenzenes and polychlorophenols impurities may play a key role in the PCBs and PCDD/Fs formation. The impurities of PCDD/Fs and PCBs in 2,4-D may increase the risk for the human and environmental health.