Decomposition of high-impact polystyrene resin in e-waste by supercritical water oxidation process with debromination of decabromodiphenyl ethane and recovery of antimony trioxide simultaneously

Abstract

In order to ensure the performance and safety of electronic products, a large number of polymeric insulation resins are used as housing materials. When electronic products are discarded as e-waste, these resins containing organobromine compounds and antimony trioxide as flame retardants are difficult to be disposed of by traditional recycling methods, due to their excellent resistance to acid, alkali, high temperature and photooxidation. It not only brings the hazardous risks for environmental protection, but also hinders the recovery of resources in e-waste. In this study, supercritical water oxidation(SCWO) process was applied to decompose waste high-impact polystyrene(HIPS) resin in e-waste combining debromination of decabromodiphenyl ethane and recovery of antimony trioxide. The results showed that HIPS could be quickly and efficiently decomposed during SCWO process. The optimum SCWO parameters were temperature of 500 ℃, holding time of 60 min, pressure of 23 MPa, and excess oxygen of 200 %, respectively. The decomposition products of HIPS were hydrocarbons, carbon dioxide and water. Meanwhile, brominated flame retardants and antimony trioxide added to the HIPS were also debrominated and recovered. Without secondary pollution, the SCWO process developed in this study could effectively achieve decomposition of HIPS resins, debromination of brominated flame retardants and recovery of antimony trioxide in one procedure.