Yang Shiying, Sun Xinrong, Jiang Yuting, Wu Sui, Zhao Dongye
Key Laboratory of Marine Environment and Ecology, Ministry of Education, Qingdao 266100, China; Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering (MEGE), Qingdao 266100, China; College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China.
Key Laboratory of Marine Environment and Ecology, Ministry of Education, Qingdao 266100, China; College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China.
Sci Total Environ. 2022 Jun 10;824:153864. doi: 10.1016/j.scitotenv.2022.153864. Epub 2022 Feb 15.
Hexabromocyclododecane (HBCD) has been listed in Annex A of the Stockholm Convention as a persistent and bio-accumulative chemical. While HBCD is often present in the solid form for its low solubility, cost-effective technologies have been lacking for the degradation of solid-phase HBCD. In this work, mechanochemical (MC) destruction of high-energy ball milling was employed for direct destruction of solid-phase HBCD, where a strong reducer, microscale zero-valent aluminum (mZVAl), was used as the co-milling agent. The new mZVAl-assisted MC process achieved complete debromination and mineralization of HBCD within 3 h milling. The optimal operating parameters were determined, including the milling atmosphere, the milling speed, the mZVAl-to-HBCD molar ratio, and the ball-to-mZVAl mass ratio. Fourier transform infrared spectrometry and Raman analyses revealed that the organic structures of HBCD were destroyed and organic bromine was completely converted into inorganic bromide, accompanied by the generation of amorphous and graphite carbon. Analysis of the milled samples by GC-MS demonstrated the absence of obvious organic matter after MC treatment, also indicating the complete degradation and conversion of HBCD to inorganic compounds. Further X-ray photoelectron spectroscopic analysis indicates that the fresh surface of mZVAl was generated upon the MC treatment, and Al(0) served as a strong reducing agent (e-donor) for reductive debromination and destruction of the carbon skeleton. The mZVAl-assisted MC milling appears promising as a non-combustion approach for effective destruction and carbonization/mineralization of solid-phase HBCD or potentially other persistent organic pollutants.
六溴环十二烷（HBCD）已被列入《斯德哥尔摩公约》附件A，属于持久性生物累积性化学物质。由于HBCD溶解度低，通常以固体形式存在，而目前缺乏经济高效的技术来降解固相HBCD。在本研究中，采用高能球磨机械化学法（MC）直接破坏固相HBCD，使用强还原剂微尺度零价铝（mZVAl）作为共研磨剂。新的mZVAl辅助MC工艺在研磨3小时内实现了HBCD的完全脱溴和矿化。确定了最佳操作参数，包括研磨气氛、研磨速度、mZVAl与HBCD的摩尔比以及球与mZVAl的质量比。傅里叶变换红外光谱和拉曼分析表明，HBCD的有机结构被破坏，有机溴完全转化为无机溴化物，同时生成了无定形碳和石墨碳。气相色谱-质谱联用仪对研磨后样品的分析表明，MC处理后没有明显的有机物残留，这也表明HBCD已完全降解并转化为无机化合物。进一步的X射线光电子能谱分析表明，MC处理后产生了mZVAl的新鲜表面，Al(0)作为强还原剂（电子供体）用于还原脱溴和破坏碳骨架。mZVAl辅助MC研磨作为一种非燃烧方法，有望有效破坏和碳化/矿化固相HBCD或其他潜在的持久性有机污染物。
