Microwave Induced Pyrolysis of Bromine Contained Printed Circuit Board Wastes

Printed Circuit Board (PCBs) wastes are a typical kind of electronic wastes. The recycling and disposal of PCBs wastes have become an important issue. Thermal degradation via pyrolysis is considered to be a feasible disposal approach. The microwave induced pyrolysis of PCBs wastes was performed in a bench scale microwave reactor with a horizontal quartz tube. The effects of reaction conditions on the pyrolysis process and pyrolytic products were investigated under different microwave power, microwave heating time and the weight ratio of SiC to PCBs. The optimum microwave pyrolysis process conditions for disposal of PCBs were determined. The liquid and solid pyrolytic products were further analyzed. The composition and surface properties of solid pyrolytic product showed that the solid product mainly contained inorganic substance, such as Si, Ca, Mg, Al, Ti and their oxide compounds. The results of GC-MS analysis of liquid pyrolytic product showed that liquid pyrolytic product contained large amounts of compounds with aromatic structure, such as phenol, biphenyl A, etc. Some substance contains Br, N and O was also detected, such as ketone, hydroxybenzene, etc. The bromine in liquid product is related with the bromide fire retarding agent in PCBs. Phenol and biphenyl A were the main component in liquid pyrolytic product which came from the pyrolysis of epoxy resin.