Printed circuit boards （PCBs） are in all electronic equipment, so with the sharp increase of electronic waste, the recovery of PCB components has become a critical research field. This paper presents a study of the ...Printed circuit boards （PCBs） are in all electronic equipment, so with the sharp increase of electronic waste, the recovery of PCB components has become a critical research field. This paper presents a study of the reclaimation and reuse of nonmetallic materials recovered from waste PCBs. Mechanical processes, such as crushing, milling, and separation, were used to process waste PCBs. Nonmetallic materials in the PCBs were separated using density-based separation with separation rates in excess of 95%. The recovered nonmetals were used to make models, construction materials, composite boards, sewer grates, and amusement park boats. The PCB nonmetal products have better mechanical characteristics and durability than traditional materials and fillers. The flexural strength of the PCB nonmetallic material composite boards is 30% greater than that of standard products. Products derived from PCB waste processing have been brought into industrial production. The study shows that PCB nonmetals can be reused in profitable and environmentally friendly ways.展开更多
Accelerated industrialization and urbanization,and unregulated disposal of waste of electric and electronic equipment（e-waste） in China have caused environmental pollution of brominated flame retardants（BFRs）.This...Accelerated industrialization and urbanization,and unregulated disposal of waste of electric and electronic equipment（e-waste） in China have caused environmental pollution of brominated flame retardants（BFRs）.This review summarized the levels,trends,and bioaccumulation characteristics of polybrominated diphenyl ethers（PBDEs） and other potential alternative BFRs including hexabromocyclododecanes（HBCDs）,1,2-bis（2,4,6-dibromophenoxy） ethane（BTBPE） and decabromodiphenylethane（DBDPE） in wildlife from China.PBDE levels in wildlife from China were generally higher than those from other parts in Asia,and were comparable to those from Europe but were lower than those from North America.However,wildlife from the e-waste recycling sites in South China and East China contained much higher PBDEs compared to other reports around the world,suggesting the heavy contamination of PBDEs in these regions.The alternative BFRs were also detected in wildlife,revealing that the animals are exposed to these chemicals,in addition to PBDEs.Temporal trends indicated by levels in marine mammals from South China suggested that PBDE levels increased from the beginning of 1990s to 2000s,but decreased from the middle of 2000s,followed by relatively steady levels.In contrast,HBCDs were found to be continuously increasing from 1997 to 2007,indicating the increasing usage of HBCDs in China in recent years.Compared to PBDE profiles found in other parts,aquatic species and birds from China contained relatively higher contributions of BDE28 and 209,respectively,suggesting the possible different usage pattern of PBDEs.Future works including keeping monitoring at a reasonable scale and frequency to make sure levels near urban centers indicative of population do not increase are needed.Additionally,focus effort on e-waste recycling regions to look for impacts and to determine if regulation/controls are resulting in lower environmental contamination,and incorporation of sentinel species in monitoring efforts are recommended.展开更多
基金the National High-Tech Research and Development (863) Program of China (No. 2004AA420120)
文摘Printed circuit boards （PCBs） are in all electronic equipment, so with the sharp increase of electronic waste, the recovery of PCB components has become a critical research field. This paper presents a study of the reclaimation and reuse of nonmetallic materials recovered from waste PCBs. Mechanical processes, such as crushing, milling, and separation, were used to process waste PCBs. Nonmetallic materials in the PCBs were separated using density-based separation with separation rates in excess of 95%. The recovered nonmetals were used to make models, construction materials, composite boards, sewer grates, and amusement park boats. The PCB nonmetal products have better mechanical characteristics and durability than traditional materials and fillers. The flexural strength of the PCB nonmetallic material composite boards is 30% greater than that of standard products. Products derived from PCB waste processing have been brought into industrial production. The study shows that PCB nonmetals can be reused in profitable and environmentally friendly ways.
基金supported by the National Natural Science Foundation of China (No. 41103054,40821003,41073081)the Earmarked Fund of the State Key Laboratory of Organic Geochemistry (No. OGL-200905)
文摘Accelerated industrialization and urbanization,and unregulated disposal of waste of electric and electronic equipment（e-waste） in China have caused environmental pollution of brominated flame retardants（BFRs）.This review summarized the levels,trends,and bioaccumulation characteristics of polybrominated diphenyl ethers（PBDEs） and other potential alternative BFRs including hexabromocyclododecanes（HBCDs）,1,2-bis（2,4,6-dibromophenoxy） ethane（BTBPE） and decabromodiphenylethane（DBDPE） in wildlife from China.PBDE levels in wildlife from China were generally higher than those from other parts in Asia,and were comparable to those from Europe but were lower than those from North America.However,wildlife from the e-waste recycling sites in South China and East China contained much higher PBDEs compared to other reports around the world,suggesting the heavy contamination of PBDEs in these regions.The alternative BFRs were also detected in wildlife,revealing that the animals are exposed to these chemicals,in addition to PBDEs.Temporal trends indicated by levels in marine mammals from South China suggested that PBDE levels increased from the beginning of 1990s to 2000s,but decreased from the middle of 2000s,followed by relatively steady levels.In contrast,HBCDs were found to be continuously increasing from 1997 to 2007,indicating the increasing usage of HBCDs in China in recent years.Compared to PBDE profiles found in other parts,aquatic species and birds from China contained relatively higher contributions of BDE28 and 209,respectively,suggesting the possible different usage pattern of PBDEs.Future works including keeping monitoring at a reasonable scale and frequency to make sure levels near urban centers indicative of population do not increase are needed.Additionally,focus effort on e-waste recycling regions to look for impacts and to determine if regulation/controls are resulting in lower environmental contamination,and incorporation of sentinel species in monitoring efforts are recommended.
