Department of Chemical and Petroleum Engineering, United Arab Emirates University, Sheikh Khalifa Bin Zayed Street, 15551, Al-Ain, United Arab Emirates.
Department of Physics, College of Education, Al- Iraqia University, Baghdad, Iraq.
Environ Sci Pollut Res Int. 2023 Sep;30(43):98300-98313. doi: 10.1007/s11356-023-29428-2. Epub 2023 Aug 22.
Legacy brominated flame retardants (BFRs) in printed circuit boards are gradually being replaced by novel BFRs (NBFRs). Safe disposal and recycling of polymeric constituents in the polymeric fractions of e-waste necessitate the removal of their toxic and corrosive bromine content. This is currently acquired through thermal recycling operations involving the pyrolysis of BFRs-containing materials with metal oxides. Nonetheless, the debromination capacity toward NBFRs is yet to be established. Thus, this study aims to address these two crucial gaps in the current knowledge pertaining to the plausible formation of brominated toxicants from the thermal decomposition of NBFRs and their thermal recycling potential. Herein, we investigate the pyrolysis of a mixture of 2,4,6-tribromophenol (TBP), allyl 2,4,6-tribromophenyl ether (ATE) and Tetrabromobisphenol A-bis (2,3-dibromo propyl ether) (TBBPA-DBPE) in the presence of acrylonitrile butadiene styrene (ABS) polymers at various loads. To demonstrate a viable debromination route, pyrolysis of NBFRs-ABS mixture with Ca(OH) was also investigated. The latter is a potent debromination agent for legacy BFRs. Upon pyrolysis with Ca(OH), the bromine content in the collected oil was reduced up to 80.49% between 25-500 °C. Products of the co-pyrolysis process generally feature non-brominated aromatic and aliphatic compounds; a finding that indicates an effective thermal recycling approach. As evident by IC measurements, no HBr emission could be detected when Ca(OH) is added to the mixture. As XRD patterns show, Ca(OH) is partially converted into CaBr. DFT calculations provide pathways for the observed surface debromination characterized by surface-assisted fission of aromatic C-Br bonds and the formation of CaBr sites. Outcomes reported herein are instrumental to designing and operating a thermal recycling facility of polymeric materials contaminated with high loads of bromine, i.e., most notably during scenarios encountered in the thermal recycling of e-waste.
印刷电路板中的传统溴化阻燃剂 (BFR) 正逐渐被新型 BFR (NBFR) 取代。为了安全处理和回收电子废物中聚合物部分的成分，需要去除其有毒和腐蚀性的溴含量。这是通过涉及含有金属氧化物的 BFR 材料热解的热回收操作来实现的。然而，NBFR 的脱溴能力尚未确定。因此，本研究旨在解决当前关于 NBFR 热分解形成溴化有毒物质及其热回收潜力的两个关键知识空白。在此，我们研究了在丙烯腈丁二烯苯乙烯 (ABS) 聚合物存在下，2,4,6-三溴苯酚 (TBP)、烯丙基 2,4,6-三溴苯醚 (ATE) 和四溴双酚 A-双 (2,3-二溴丙基醚) (TBBPA-DBPE) 的混合物在不同负载下的热解情况。为了展示可行的脱溴途径，我们还研究了 NBFR-ABS 混合物与 Ca(OH)的热解。后者是传统 BFR 的有效脱溴剂。在用 Ca(OH)进行热解时，在 25-500°C 之间收集的油中的溴含量减少了 80.49%。共热解过程的产物通常具有非溴化的芳香族和脂肪族化合物；这一发现表明了一种有效的热回收方法。正如 IC 测量所表明的，当混合物中加入 Ca(OH)时，无法检测到 HBr 排放。正如 XRD 图谱所示，Ca(OH)部分转化为 CaBr。DFT 计算提供了观察到的表面脱溴途径，其特征是芳族 C-Br 键的表面辅助裂变和 CaBr 位的形成。本文报告的结果对于设计和操作热回收设施具有重要意义，该设施污染有大量溴，尤其是在电子废物的热回收过程中遇到的情况。
