Mechanistic insights into catalysis of in-situ iron on pyrolysis of waste printed circuit boards: Comparative study of kinetics, products, and reaction mechanism

Jingxin Liu; Hanlin Wang; Wenjuan Zhang; Teng Wang; Meng Mei; Si Chen; Jinping Li

doi:10.1016/j.jhazmat.2022.128612

Mechanistic insights into catalysis of in-situ iron on pyrolysis of waste printed circuit boards: Comparative study of kinetics, products, and reaction mechanism

J Hazard Mater. 2022 Jun 5:431:128612. doi: 10.1016/j.jhazmat.2022.128612. Epub 2022 Mar 2.

Authors

Jingxin Liu¹, Hanlin Wang², Wenjuan Zhang³, Teng Wang¹, Meng Mei¹, Si Chen¹, Jinping Li¹

Affiliations

¹ School of Environmental Engineering, Wuhan Textile University, Wuhan 430073, China; Engineering Research Centre for Clean Production of Textile Dyeing and Printing, Ministry of Education, Wuhan Textile University, Wuhan 430073, China.
² School of Environmental Engineering, Wuhan Textile University, Wuhan 430073, China.
³ School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China; Department of Materials Engineering, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada. Electronic address: zwjuan1109@163.com.

PMID: 35259695
DOI: 10.1016/j.jhazmat.2022.128612

Abstract

Pyrolysis is a potential recovery method for waste printed circuit boards (WPCBs), but the organic brominated products are toxic and hazardous. Iron has been used as a catalyst for debromination from pyrolysis oil, but the effects of in-situ iron on WPCBs pyrolysis is still not well understood. Herein, the pyrolysis mechanism for laminates of PCBs in the absence and presence of iron was studied via analyzing pyrolysis characteristics, kinetics, and products. According to the thermogravimetry experiments, pyrolysis of all samples could be divided into four stages, and iron accelerated the pyrolysis reaction by decreasing the activation energy as calculated using the Starink method. Volatiles released during the heating process were continuously determined by TG-FTIR-MS, and products generated at different pyrolysis temperatures were collected and characterized. The obtained results exhibited that iron promoted the generation of gaseous products and facilitated the conversion of organic bromides to inorganic bromides. Therefore, retaining iron was beneficial to energy saving and environmental protection for WPCBs pyrolysis. In addition, the decomposition mechanisms of brominated epoxy resin with and without iron were proposed. This work would contribute to the improvement and application of WPCBs pyrolysis technology.

Keywords: Brominated epoxy resin; Catalytic pyrolysis; Iron; Laminate; Waste printed circuit boards.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Bromides
Catalysis
Electronic Waste* / analysis
Iron
Kinetics
Pyrolysis*

Substances

Bromides
Iron