Department of Plant and Soil Sciences, University of Delaware, Newark, DE 19716, USA.
J Hazard Mater. 2012 May 30;217-218:187-93. doi: 10.1016/j.jhazmat.2012.03.012. Epub 2012 Mar 16.
2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) are common contaminants around active military firing ranges. Dissolution of these compounds is usually the first step prior to their spreading in subsurface environments. Nevertheless, dissolution of individual TNT, RDX, and HMX under continuous flow conditions has not been well investigated. This study applied spectral confocal microscopy to observe and quantify the dissolution of TNT, RDX, and HMX (<100 μm crystals) in micromodel channels. Dissolution models were developed to describe the changes of their radii, surface areas, volumes, and specific surface areas as a function of time. Results indicated that a model incorporating a resistance term that accounts for the surface area in direct contact with the channel surfaces (and hence, was not exposed to the flowing water) described the dissolution processes well. The model without the resistance term, however, could not capture the observed data at the late stage of TNT dissolution. The model-fitted mass transfer coefficients were in agreement with the previous reports. The study highlights the importance of including the resistance term in the dissolution model and illustrates the utility of the newly developed spectral imaging method for quantification of mass transfer of TNT, RDX, and HMX.
2,4,6-三硝基甲苯（TNT）、六氢-1,3,5-三硝基-1,3,5-三嗪（RDX）和八氢-1,3,5,7-四硝基-1,3,5,7-四氮杂环辛烷（HMX）是现役军事射击场周围常见的污染物。这些化合物的溶解通常是在它们在地下环境中扩散之前的第一步。然而，连续流动条件下单个 TNT、RDX 和 HMX 的溶解尚未得到很好的研究。本研究应用光谱共焦显微镜观察和定量分析了微通道中<100 μm 晶体的 TNT、RDX 和 HMX 的溶解情况。建立了溶解模型来描述它们的半径、表面积、体积和比表面积随时间的变化。结果表明，一个包含考虑与通道表面直接接触的表面积的阻力项的模型（因此，未暴露于流动水）可以很好地描述溶解过程。然而，没有阻力项的模型不能在 TNT 溶解的后期阶段捕捉到观察到的数据。模型拟合的传质系数与先前的报告一致。该研究强调了在溶解模型中包含阻力项的重要性，并说明了新开发的光谱成像方法在定量 TNT、RDX 和 HMX 传质方面的应用。
