Mechanochemical degradation of brominated flame retardants in waste printed circuit boards by Ball Milling

• Published in: Journal of hazardous materials Vol. 385; p. 121509
• Main Authors: Wang, Rui, Zhu, Zhixin, Tan, Shufei, Guo, Jie, Xu, Zhenming
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05.03.2020
• Subjects: BFRs; Debromination; Mechanochemistry; Recycling; WPCBs; Debromination; BFRs; Recycling; WPCBs; Mechanochemistry
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2019.121509

[Display omitted] •Mechanochemical reactions occurred in the process of crushing WPCBs.•The increase of revolution speed and time improved degradation efficiency.•Bromine distributed evenly on the surface of submicron particles after milling.•Debromination pathway of PBDEs in WPCBs under ball milling was proposed. Degradation of brominated flame retardants (BFRs) in waste printed circuit boards (WPCBs) occurred due to mechanical force during the crushing process. In this study, a planetary ball-milling simulation experiment was designed to explore the mechanochemical debromination process of BFRs in WPCBs. The results showed that CaO had a better debromination performance than MgO and the mixture of Fe + SiO2, and high revolution speed and low mass ratio of WPCBs to CaO promoted the degradation of BFRs. After milling for 1 h, the particle size distribution was stable while the debromination efficiency increased with the increase of milling time. Ball milling promoted the migration of bromine from the inside to the new surface of WPCBs powder, and submicron particles adhered to the micron size aggregates. The polybrominated diphenyl ethers (PBDEs) detection showed that the concentrations of most PBDE congeners decreased with the increase of milling time, and a possible degradation pathway was proposed according to the experimental results. All the results provided new data for the mechanism of degradation of BFRs in WPCBs during the mechanical crushing process.