期刊
WASTE MANAGEMENT
卷 102, 期 -, 页码 464-473出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.wasman.2019.11.011
关键词
Waste printed circuit board; Brominated epoxy resin; Subcritical acetic acid; Swelling; Catalytic degradation
资金
- National Natural Science Founds of China [51508165]
- Key scientific research projects of henan higher education institutions [14A610001]
- Doctoral fund project of Henan polytechnic university [B2014-073]
Waste printed circuit boards (WPCBs) contain a large amount of brominated epoxy resins (BERs), which may cause environmental problems. However, BERs degradation under mild conditions is challenging due to the good thermal and chemical stabilities of BERs. This study proposes a mild and efficient method that uses subcritical acetic acid (220 degrees C-260 degrees C, 2.6-3.6 MPa) to decompose BERs. BERs swell quickly at 200 degrees C and are thoroughly decomposed into bisphenol A and phenol at 220 degrees C when the acetic acid mass concentration and holding time are fixed at 49.90% and 1 h, respectively. Experimental results show that subcritical acetic acid has excellent swelling and catalytic degradation effects on BERs. The quick swelling of BERs allows the free migration of the catalyst in the epoxy network and thus significantly enhances the catalytic degradation effect. Therefore, BERs can be thoroughly decomposed by subcritical acetic acid under mild conditions. Temperature and acetic acid concentration are the major parameters that control the resin degradation rate. Bromine-free oil phase products are obtained at >= 240 degrees C. The possible decomposition pathway of BERs in subcritical acetic acid is also investigated. Most of the bromine is transformed into HBr and enriched in the aqueous phase. In conclusion, the proposed mild method could be used as a novel practical and industrial procedure for the degradation and debromination of BERs. (C) 2019 Elsevier Ltd. All rights reserved.
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