Pyrolysis and utilization of nonmetal materials in waste printed circuit boards: Debromination pyrolysis, temperature-controlled condensation, and synthesis of oil-based resin

The rapid replacement of electric and electronic equipment has produced large amount of waste printed circuit boards (WPCBs). At present, physical and mechanical methods are widely used to recover valuable metals from WPCBs. Unfortunately, produced nonmetal materials (NMMs) were typically hazardous waste and were usually disposed by landfill. Considering the characteristics of structure and composition of NMMs, debromination pyrolysis was regarded as the appropriate technique to decompose organics. However, pyrolysis oil and pyrolysis residue were still typically hazardous and difficult to disposal or recycle. Hence, we proposed a novel integrated method to reuse NMMs. The results showed that temperature-controlled condensation method was effective to separate pyrolysis oil. Besides, bromine was removed from organics and formed CaBr2. Pyrolysis oil was used to synthesize oil-based resin. FT-IR, H-1 and C-13 NMR and TG analysis results indicated that oil-based resin had the same structure and thermostability with commercial resin, which suggested that oil-based rein had economic value. In addition, CaBr2 in residual could be recycled by water leaching and filter residues can be used as ideal reinforcing material for building materials. This study raises a comprehensive method to utilize NMMs and recover value materials effectively, sustainably and environmentally friendly.