The Content And Leaching Characteristics Of PBDEs And Metals From Waste Printed Circuit Boards

Polybrominated diphenyl ethers (PBDEs) and metals contained in the waste printed circuit boards (WPCBs) could leach out or migrate into the environment when WPCBs stacked outstides or were recycled by hydrometallurgy, resulting in pollutions of persistent organic pollutants (POPs) and heavy metals. In this paper, the content of PBDEs in printed circuit boards (PCBs) with different ages, types and producing countries were studied, and leaching experiments of WPCBs with different solvents were conducted to discuss the leaching characteristics of PBDEs and metals.The composition and concentrations of PBDEs in PCBs collected from an E-waste dismantling area in Taizhou, Zhejiang were investigated, and PBDEs congeners were identified and quantified by GC-NCI-MS. The results showed that higher concentration of PBDEs was found in the PCBs produced before 2006, and PCBs in keyboards contained a different content of PBDEs congeners with higher concentrations when compared to PCBs in instruments. The study also found that PBDEs in PCBs made in Japan contains primarily Tetra-BDE and Penta-BDE, while Deca-BDE predominates with the highest concentration in PCBs made in China.The leaching characteristics of PBDEs were investigated using various solvents including toluene, ethanol, trichloroethylene solution (TCE) and actual landfill leachate. The concentrations of eight PBDEs congeners were studied. The results showed that after reaching the equilibrium (toluene:48 h, ethanol:96 h, TCE:240 h, landfill leachate:20 d), the concentrations of theΣ8PBDEs leached from particles of crushed WPCBs (diameter ranging from 180μm to 380μm) were 2320.06 mg/kg,1946.17 mg/kg, and 79.38 mg/kg in toluene, ethanol and TCE, as well as 1042.12μg/kg and 23.63μg/kg in untreated and treated actual landfill leachate, respectively. Among PBDEs congeners, BDE99 and BDE47 were the main congeners. The particle size had significant effect on PBDEs leaching with the conclusion that the smaller the particles' diameter, the easier for the PBDEs be leached out.The concentrations of metals contained in the PCBs were determined by AAS. The results showed that the metals content in PCBs was up to 37.3%, and Cu, Sn, Fe, Pb and Zn are the main metals. Metals can be leaching out easily using a strong acidic solution (pH=1). While, low concentrations of Zn and Cu was detected in the leachate using a simulation solution of acid rain (pH=4), and the concentrations of metals are all below the detection limit (0.4 mg/kg) when using a neutral solution (pH=7).