| Polybrominated Diphenyl Ethers (PBDEs) had become a hot topic on the environmental field due to its environmental persistence, lipotropy, bioaccumulation and toxic effects on living beings and human. Along with the swift development of electronic information industry, the output of electronic wastes increases fast. The large amounts of PBDEs from electronic wastes would release into the environment by leaching of rainwater, surface water and landfill leachate with different disposal scene, and leading to ecological problems. Meanwhile, it will threat to a human health when PBDEs were accumulated in human body through breath and food chain.At present, the research of PBDEs were mainly focused on quantitative detection, typical distribution, environmental behaviors, toxic effect and other aspects, but, research on leaching characteristics of PBDEs are scarce. Thus, in this study, based on the establishing analysis methods of PBDEs of electronic wastes sample and leach liquor, the leaching characteristics of PBDEs from e-waste were simulated under different levels of many factors by leaching tests, so as to provide a theoretical basis for standardizing leaching test of PBDEs from solid waste and assess the risks of PBDEs in actual environment, which had an important practical significance to control of persistent organic pollution, rational disposal and scientific management electronic wastes in our country. The results are shown as follows:(1) The contents of PBDEs from waste circuit boards and printer housing plastics were relatively high, and Tetra-BDEs were mainly PBDEs congeners. But the contents of PBDEs from waste computer housing plastics was relatively low. BDE209was the main component of PBDEs congeners from waste washing-machine housing plastics and the contents of other BDE congeners were very low.(2) There were four congeners (BDE28, BDE47, BDE66, BDE99) were detected by using mixture of sulfuric acid and nitric acid, citric acid, tartaric acid, oxalic acid, acetic acid buffer solution as leaching agent respectively; and the leach quantity of PBDEs were very low. In contrast with the former leaching agents, seven PBDEs congeners (BDE28, BDE47, BDE66, BDE85, BDE99, BDE100, BDE153) were detected by using the commercial humic acid were used, and the leaching content were much higher relatively.(3) Leaching rate of PBDEs were10-4～10-3by using humic acid solution as extractant in waste printer housing and circuit board sample, which indicated that PBDEs in electronic wastes in leaching of release to the environment was a slow process. Different solubilities between different PBDEs homologues caused the differ of leaching characteristics, BDE28、BDE47、BDE66which had relatively large solubilities had a relatively high leaching rate, however, low solubility components in a short period test had not leaching at all or had a low leaching rate.(4) Within the scope of the experimental design, six kinds of PBDEs congeners (BDE28, BDE47, BDE66, BDE85, BDE99, BDE153) were detected in lixivium of waste printer housing sample. There were positive correlation among PBDEs leaching concentrations within the range of experimental parameters and DOC concentrations, leaching time and liquid-to-solid ratio respectively, and negatively correlated with particle diameter. Final, the leaching concentrations of PBDEs under neutral condition were better than acidic condition.(5) Within the scope of the experimental design, seven kinds of PBDEs congeners (BDE28, BDE47, BDE66, BDE85, BDE99, BDE100, BDE153) were detected in lixivium of waste circuit board sample. The leaching of PBDEs increased with increasing of concentration of DOC, increasing of liquid-solid ratio and decreasing of waste particle size; with the increase of leaching time, leaching amounts had not changed a lot; the leaching content under neutral conditions were higher than that of acidic conditions; the leach quantity were in the order:standing>flip oscillation>horizontal oscillation under different ways of leaching methods. |
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