分别以三乙醇胺(TEA)和一乙醇胺(MEA)作为氢源,六氯苯(HCB)作为模型化合物,研究了在密闭体系下飞灰中氯代芳烃的加氢脱氯作用.考察了TEA或MEA添加量、热处理温度和时间对脱氯效率的影响,证实有明显的脱氯反应发生.当MEA或TEA添加量为8%时,经过250℃,2 h热处理,脱氯效率分别可达94.7%和78.6%.MEA相对TEA的脱氯效果更显著,与二者抑制PCDD/F形成的活性一致.在250℃下处理1 h,4%MEA的添加量即可得到78.6%的脱氯效率.推测脱氯机理可能为氧化加成/还原消除反应.该研究结果显示MEA在开发温度更低的飞灰低温热处理技术方面有巨大应用前景,同时也有助于更好地解释醇胺类物质的抑制机理.
In the present study,the hydrodechlorination of polychlorinated aromatics on fly ash with triethanolamine(TEA) and ethanolamine(MEA) was carried out.The effects of the alcoholamine content,reaction temperature and reaction time on dechlorination efficiency were investigated.It was confirmed that the dechlorination reaction had occurred.After 2 h reaction with 8% MEA or TEA at 250℃,the dechlorination efficiency of HCB reached 94.7% and 78.6%,respectively.MEA was more efficient than TEA,which was consistent with their inhibition abilities.The dechlorination extent was up to 78.6% at 250℃ for 1 h with 4% MEA.Oxidative addition/reductive elimination were proposed to be a major dechlorination reaction of HCB on fly ash at low temperature.The results indicated that alcohol amines,especially MEA,have a great potential use in detoxifying fly ash at lower temperature.Furthermore,these findings are helpful for better understanding of the inhibition mechanism of alcohol amines.