摘要
采用中试试验台的水平滚动式球磨机,对高浓度多氯联苯(PCBs)污染土壤进行机械化学法处置.以氧化钙(Ca O)为主要添加剂成分,对比有无石英砂(SiO_2)助剂,混合球磨PCBs污染土壤.使用高分辨气相色谱/质谱联用仪(HRGC/MS)检测,分析球磨机械化学反应前后土壤中PCBs的去除率和二英(PCDD/Fs)的合成率.结果表明,采用水平滚动式球磨机对土壤进行20 h研磨后,对于单一Ca O添加球磨工况,PCBs总量和毒性当量(WHO-TEQ)分别减少了65%和73%;添加石英砂助剂后(Ca O-SiO_2工况),PCBs总量和WHOTEQ的去除率分别达到了74%和78%,证实水平滚动式低速球磨能有效降解PCBs,且SiO_2有助于Ca O添加剂机械化学去除土壤中PCBs.对球磨处理前后的PCDD/Fs生成量进行比较,结果表明,在反应初期的5 h内,部分PCBs氧化为高氯代的PCDFs,导致PCDD/Fs总量和毒性当量(I-TEQ)有所上升;球磨超过5 h后,PCDD/Fs开始发生降解反应.在保证充足的球磨反应时间条件下,机械化学处理PCBs可以克服传统PCBs热处置的首要缺陷——PCDD/Fs的二次合成问题.
Mechanochemical decomposition of PCBs in soil was studied using a horizontal mill.Grinding a mixture of PCBs and Ca O with or without quartz was conducted. The removal of PCBs and formation of PCDD / Fs during ball milling were judged by HRGC / MS. After 20 h of milling,total PCBs concentration and WHO-TEQ of PCBs decreased by 65% and 73% with Ca O additive,while the removal rate of the total PCBs and the WHO-TEQ reached 74% and 78% with Ca O-SiO2 additives,indicating that effective decomposition of PCBs was achieved by applying a horizontal mill, and the addition of quartz facilitated dechlorination. Formation of PCDD / Fs during mechanochemical destruction of PCBs was evaluated. The concentration of PCDD / Fs and I-IEQ increased in the first 5 h,caused by the conversion of PCBs to high chlorinated PCDFs. They then decreased with grinding time. With sufficient grinding time,the problem of PCDFs formation can beovercome during mechanochemical degradation of PCBs.
出处
《环境化学》
CAS
CSCD
北大核心
2016年第4期607-614,共8页
Environmental Chemistry
基金
国家重点基础研究发展项目(2011CB201500)
国家自然科学基金(51276162)资助~~
关键词
土壤修复
机械化学
多氯联苯
氧化钙
石英
二噁英
soil remediation
mechanochemical
polychlorinated biphenyls
CaO
quartz
PCDD/Fs
