Emission behaviors of nitro- and oxy-polycyclic aromatic hydrocarbons during pyrolytic disposal of electronic wastes

Emission factors (EFs) of polycyclic aromatic hydrocarbon (PAH) derivatives (12 nitro-PAHs and 4 oxy-PAHs) during the pyrolysis of two types of electronic waste (E-waste) were measured. Compositional profile, particle size distribution, gas-particle partitioning, correlations with precursor species and influences of pyrolytic temperature were investigated. The derivative products were dominated by oxy-PAHs. The averaged EFs of oxy-PAHs were 3.37 +/- 4.10 mu g/g and 32.6 +/- 18.1 mu g/g for PWBs and plastic casings, respectively, and those of nitro-PAHs were 85.7 +/- 92.4 ng/g and 83.3 +/- 69.7 ng/g, respectively. Most EFs of derivative species significantly correlated with their corresponding parent PAHs (p < 0.05), except a few cases, indicating formation of derivatives via related reactions of parent species. Most nitro-PAHs occurred in fine particles with the size < 2.1 mu m, and oxy-PAHs were prevailing in fine particles with the size between 0.4 mu m and 2.1 mu m. Proportions of oxy-PAHs in particulate phase, especially those with higher molecular weight, were noticeably greater than those of the corresponding parent species. Below 480 degrees C, there was no evident difference in the EFs of PAH derivatives, while the EFs noticeably increased from 520 degrees C. With the increasing temperature, the majority of oxy-PAHs still occurred on finer particles, while the contribution of coarser particles tended to increase. (C) 2019 Elsevier Ltd. All rights reserved.