Co-pyrolysis of waste printed circuit boards with iron compounds for Br-fixing and material recovery

Waste printed circuit boards (WPCBs) were co-pyrolyzed with iron oxides and iron salts. Solid, liquid, and gaseous products were collected and characterized. Co-pyrolysis with FeCl₂, FeCl₃, or FeSO₄ was able to increase the yield of liquid product which was rich in phenol and its homologues. Also, the addition of co-pyrolysis reagents reduced the release of brominated organics to liquid as Br was either fixed as FeBr₃ in solids or released as HBr. In particular, FeCl₂ showed the best ability to reduce the release of Br-containing organics to liquid compared with FeCl₃ and FeSO₄. Solid residuals were rich in iron oxides, glass fibers, and charred organics with surface areas of 20.6-26.5 m²/g. CO₂ together with a small amount of CH₄ and H₂ were detected in the gaseous products. Overall, co-pyrolysis could improve the quantity and quality of liquid oil which could be reused as chemical or energy sources. Pyrolysis of waste printed circuit board was promising as a method for recycling.