Bromine Migration and Product Analysis of Waste Printed Circuit Boards during Microwave Steam‐Gasification‐Assisted Pyrolysis

• Published in: ChemistrySelect (Weinheim) 2023-09, Vol.8 (33), p.n/a
• Main Authors: Li, Chunyu, Liu, Chengfei, Xia, Hongying, Zeng, Kangqing, Zhang, Libo
• Format: Article
• Language: English
• Subjects: Bromine removal; Microwave pyrolysis; Product analysis; steam atmosphere; Waste printed circuit boards
• ISSN: 2365-6549; 2365-6549
• DOI: 10.1002/slct.202301327

Bromine in waste printed circuit boards has caused serious harm to the environment. How to deal with it safely is a problem. In this paper, the debromination of waste printed circuit boards by microwave gasification pyrolysis was studied, and the properties of pyrolysis products and the migration of bromine were analyzed. The optimum pyrolysis conditions of microwave steam atmosphere were 600 °C, 1000 W, 50 min, 2 mL/min. Compared with conventional pyrolysis and conventional steam pyrolysis, less solid products (60.39 wt %) were obtained, and more metal copper was enriched. The content increased from 27.46 % and 28.35 % to 30.63 %, respectively, and the diffraction peak intensity of copper was also enhanced. There is no obvious change in the type of functional groups of the solid product, and its microscopic morphology is smoother. Compared with conventional pyrolysis, the phenolic compounds in pyrolysis oil decreased, and increased compared with conventional steam pyrolysis. The content of H2 in the pyrolysis gas increased significantly, and the content of CO decreased significantly. Compared with conventional pyrolysis, the bromine content in pyrolysis gas and pyrolysis oil decreased from 94.5 % and 5.5 % to 1 %, respectively, and more bromine (98 %) in the raw material entered the aqueous solution. In this work, an efficient technology for removing bromine from waste circuit boards by microwave steam assisted pyrolysis was found. Through microwave steam assisted pyrolysis, the brominated flame retardant containing organic bromide in waste circuit boards was acted on to make it react quickly, and the optimum process conditions were optimized by single factor variable method.