Characteristics of exhaust gas, liquid products, and residues of printed circuit boards using the pyrolysis process.
BACKGROUND
The pyrolytic method was employed to recycle metals and brominated compounds blended into printed circuit boards (PCBs).


METHODS
PCBs were crushed into pieces 4.0-4.8 mm in size, and the crushed pieces were pyrolyzed at temperatures ranging from 200 to 500 degrees C. The compositions of pyrolytic residues, liquid products, and exhaust were analyzed by inductively coupled plasma atomic emission spectrometer, inductively coupled plasma mass spectrometry, and gas chromatography-mass spectrometry. Pyrolytic exhaust was collected by an impinger system in an ice bath cooler to analyze the composition fraction of the liquid product, and uncondensable exhaust was collected for gas constituent analysis.


RESULTS
Phenol, methyl-phenol, and bromo-phenol were attributed mainly to the liquid product. Metal content was low in the liquid product. In addition, CO, CO(2), CH(4), and H(2) were the major components of pyrolytic exhaust.


CONCLUSIONS
Brominated and chlorinated compounds-i.e., dichloromethane, trans-1,2 dichloroethylene, cis-1,2 dichloroethylene, 1,1,1-trichloroethane, tetrachloromethane, bromophenol, and bromoform-could be high, up to the several parts per million (ppm) level. Low molecular weight volatile organic compounds (VOCs)-i.e., methanol, acetone, ethyl acetate, acrylonitrile, 1-butene, propene, propane, and n-butane-contributed a large fraction of VOCs. The concentrations of toluene, benzene, xylene, ethylbenzene, and styrene were in the ppm range.
Chiang
Hung-Lung
HL
Department of Health Risk Management, China Medical University, Taichung, 40402, Taiwan. hlchiang@mail.cmu.edu.tw
Lo
Cho-Ching
CC
Ma
Sen-Yi
SY
D001272:Atmosphere / Q000737:chemistry; D055615:Electrical Equipment and Supplies; D004785:Environmental Pollutants / Q000032:analysis / Q000737:chemistry*; D017745:Incineration / Q000379:methods*; D007220:Industrial Waste / Q000032:analysis*; D007700:Kinetics; D055549:Volatile Organic Compounds / Q000032:analysis / Q000737:chemistry*
D004785:Environmental Pollutants; D007220:Industrial Waste; D055549:Volatile Organic Compounds