Huang Qiuyuan, Dong Hailiang, Towne Rachael M, Fischer Timothy B, Schaefer Charles E
Department of Geology and Environmental Earth Science, Miami University, Oxford, OH 45056, United States.
Department of Geology and Environmental Earth Science, Miami University, Oxford, OH 45056, United States.
J Contam Hydrol. 2014 Apr;159:36-46. doi: 10.1016/j.jconhyd.2014.01.010. Epub 2014 Feb 12.
In situ chemical oxidation using permanganate has frequently been used to treat chlorinated solvents in fractured bedrock aquifers. However, in systems where matrix back-diffusion is an important process, the ability of the oxidant to migrate and treat target contaminants within the rock matrix will likely determine the overall effectiveness of this remedial approach. In this study, a series of diffusion experiments were performed to measure the permanganate diffusion and reaction in four different types of sedimentary rocks (dark gray mudstone, light gray mudstone, red sandstone, and tan sandstone). Results showed that, within the experimental time frame (~2 months), oxidant migration into the rock was limited to distances less than 500 μm. The observed diffusivities for permanganate into the rock matrices ranged from 5.3 × 10(-13) to 1.3 × 10(-11) cm(2)/s. These values were reasonably predicted by accounting for both the rock oxidant demand and the effective diffusivity of the rock. Various Mn minerals formed as surface coatings from reduction of permanganate coupled with oxidation of total organic carbon (TOC), and the nature of the formed Mn minerals was dependent upon the rock type. Post-treatment tracer testing showed that these Mn mineral coatings had a negligible impact on diffusion through the rock. Overall, our results showed that the extent of permanganate diffusion and reaction depended on rock properties, including porosity, mineralogy, and organic carbon. These results have important implications for our understanding of long-term organic contaminant remediation in sedimentary rocks using permanganate.
使用高锰酸盐进行原位化学氧化经常被用于处理裂隙基岩含水层中的氯化溶剂。然而，在基质反向扩散是一个重要过程的系统中，氧化剂在岩石基质中迁移并处理目标污染物的能力可能会决定这种修复方法的整体有效性。在本研究中，进行了一系列扩散实验，以测量高锰酸盐在四种不同类型沉积岩（深灰色泥岩、浅灰色泥岩、红色砂岩和棕褐色砂岩）中的扩散和反应。结果表明，在实验时间框架内（约2个月），氧化剂向岩石中的迁移仅限于距离小于500μm的范围。观察到的高锰酸盐在岩石基质中的扩散系数范围为5.3×10⁻¹³至1.3×10⁻¹¹cm²/s。通过考虑岩石氧化剂需求和岩石的有效扩散系数，这些值得到了合理预测。由于高锰酸盐还原与总有机碳（TOC）氧化相结合，形成了各种作为表面涂层的锰矿物，并且所形成的锰矿物的性质取决于岩石类型。处理后的示踪剂测试表明，这些锰矿物涂层对通过岩石的扩散影响可忽略不计。总体而言，我们的结果表明，高锰酸盐扩散和反应的程度取决于岩石性质，包括孔隙率、矿物学和有机碳。这些结果对于我们理解使用高锰酸盐对沉积岩中有机污染物的长期修复具有重要意义。
