Monteil-Rivera Fanny, Paquet Louise, Halasz Annamaria, Montgomery Michael T, Hawari Jalal
Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount Avenue, Montreal, Quebec, Canada.
Environ Sci Technol. 2005 Dec 15;39(24):9725-31. doi: 10.1021/es051315n.
RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) and HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) are cyclic nitramines ((CH2NNO2)n; n = 3 or 4, respectively) widely used as energetic chemicals. Their extensive use led to wide environmental contamination. In contrast to RDX, HMX tends to accumulate in soils due to its unique recalcitrance. In the present study, we investigated the potential of zerovalent iron (ZVI) to transform HMX under anoxic conditions. HMX underwent a rapid transformation when added in well-mixed anoxic ZVI-H2O batch systems to ultimately produce formaldehyde (HCHO), ammonium (NH4+), hydrazine (NH2NH2), and nitrous oxide (N2O). Time course experiments showed that the mechanism of HMX transformation occurred through at least two initial reactions. One reaction involved the sequential reduction of N-NO2 groups to the five nitroso products (1NO-HMX, cis-2NO-HMX, trans-2NO-HMX, 3NO-HMX, and 4NO-HMX). Another implied ring cleavage from either HMX or 1NO-HMX as demonstrated by the observation of methylenedinitramine (NH(NO2)CH2NH(NO2)) and another intermediate that was tentatively identified as (NH(NO2)CH2N(NO)CH2NH-(NO2)) or its isomer (NH(NO)CH2N(NO2)CH2NH(NO2)). This is the first study that demonstrates transformation of HMX by ZVI to significant amounts of NH2NH2 and HCHO. Both toxic products seemed to persist under reductive conditions, thereby suggesting that the ultimate fate of these chemicals, particularly hydrazine, should be understood prior to using zerovalent iron to remediate cyclic nitramines.
黑索金（六氢-1,3,5-三硝基-1,3,5-三嗪）和奥克托今（八氢-1,3,5,7-四硝基-1,3,5,7-四氮杂环辛烷）是环状硝胺（(CH2NNO2)n；n分别为3或4），被广泛用作含能化学品。它们的广泛使用导致了广泛的环境污染。与黑索金不同，奥克托今由于其独特的难降解性而倾向于在土壤中积累。在本研究中，我们研究了零价铁（ZVI）在缺氧条件下转化奥克托今的潜力。当将奥克托今添加到充分混合的缺氧ZVI-H2O间歇体系中时，它会迅速转化，最终生成甲醛（HCHO）、铵（NH4+）、肼（NH2NH2）和一氧化二氮（N2O）。时间进程实验表明，奥克托今转化的机制至少通过两个初始反应发生。一个反应涉及N-NO2基团依次还原为五种亚硝基产物（1NO-奥克托今、顺式-2NO-奥克托今、反式-2NO-奥克托今、3NO-奥克托今和4NO-奥克托今）。另一个反应意味着从奥克托今或1NO-奥克托今发生环裂解，这通过观察到亚甲基二硝胺（NH(NO2)CH2NH(NO2)）以及另一种暂定为(NH(NO2)CH2N(NO)CH2NH-(NO2))或其异构体（NH(NO)CH2N(NO2)CH2NH(NO2)）的中间体得以证明。这是第一项证明ZVI将奥克托今转化为大量NH2NH2和HCHO的研究。这两种有毒产物似乎在还原条件下持续存在，因此表明在使用零价铁修复环状硝胺之前，应该了解这些化学品的最终归宿，尤其是肼。
