Inhibition of polybrominated dibenzo-p-dioxin and dibenzofuran formation from the pyrolysis of printed circuit boards.
Waste printed circuit boards containing brominated flame retardants were pyrolyzed in a high-temperature melting system to observe the formation behaviors of polybrominated dibenzo-p-dioxins (PBDDs) and dibenzofurans (PBDFs). In this study, the results showed that the formation of PBDD/ Fs during pyrolysis can be destroyed under controlled primary combustion conditions. There were two significant factors that influenced the extent of PBDD/F formation. The first factor was temperature. The results showed that, both the total PBDD/F content in the bottom ash and the total PBDD/F emission factor from the flue gas decrease by approximately 50% with an increase of the pyrolysis temperature from 850 to 1200 degrees C. The second factor was the addition of CaO. The possible mechanism involves the reaction between CaO and HBr to form the solid-phase product CaBr2. Thus, the addition of CaO is effective in adsorbing HBr and results in the inhibition of PBDD/F synthesis by more than 90% and further prevents the acid gases (HCl and HBr) that corrode the equipment. In conclusion, due to the persistence and toxicity of PBDD/Fs, a combined regulation for controlling both PCDD/Fs and PBDD/Fs is of great importance for environmental protection issues.
Lai
Yi-Chieh
YC
Department of Environmental Engineering and Sustainable Environmental Research Center, National Cheng Kung University, Tainan 70101, Taiwan, Republic of China.
Lee
Wen-Jhy
WJ
Li
Hsing-Wang
HW
Wang
Lin-Chi
LC
Chang-Chien
Guo-Ping
GP
D000393:Air Pollutants / Q000032:analysis / Q000737:chemistry*; D001572:Benzofurans / Q000032:analysis / Q000737:chemistry*; D001965:Bromides / Q000737:chemistry; D017610:Calcium Compounds / Q000737:chemistry; D004784:Environmental Monitoring; D018054:Hydrobromic Acid / Q000737:chemistry; D006851:Hydrochloric Acid / Q000737:chemistry; D017745:Incineration; D007700:Kinetics; D010087:Oxides / Q000737:chemistry; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry*; D013696:Temperature
D000393:Air Pollutants; D001572:Benzofurans; D001965:Bromides; D017610:Calcium Compounds; D010087:Oxides; D000072317:Polychlorinated Dibenzodioxins; D012989:Soil Pollutants; D018054:Hydrobromic Acid; C113019:calcium bromide; C023614:dibenzofuran; C016538:lime; D006851:Hydrochloric Acid