Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, NC 27599-7431, USA.
J Contam Hydrol. 2011 Sep 25;126(1-2):72-84. doi: 10.1016/j.jconhyd.2011.07.005. Epub 2011 Jul 31.
Cosolvent flushing is a technique that has been proposed for the removal of hydrophobic organic contaminants in the subsurface. Cosolvents have been shown to dramatically increase the solubility of such compounds compared to the aqueous solubility; however, limited data are available on the effectiveness of cosolvents for field-contaminated media. In this work, we examine cosolvent flushing for the removal of polycyclic aromatic hydrocarbons (PAHs) in soil from a former manufactured gas plant (FMGP). Batch studies confirmed that the relationship between the soil-cosolvent partitioning coefficient (K(i)) and the volume fraction of cosolvent (f(c)) followed a standard log-linear equation. Using methanol at an fc of 0.95, column studies were conducted at varying length scales, ranging from 11.9 to 110 cm. Removal of PAH compounds was determined as a function of pore volumes (PVs) of cosolvent flushed. Despite using a high f(c), rate and chromatographic effects were observed in all the columns. PAH effluent concentrations were modeled using a common two-site sorption model. Model fits were improved by using MeOH breakthrough curves to determine fitted dispersion coefficients. Fitted mass-transfer rates were two to three orders of magnitude lower than predicted values based on published data using artificially contaminated sands.
共溶剂冲洗是一种已被提出用于去除地下水中疏水性有机污染物的技术。与水溶解度相比，共溶剂已被证明能显著提高此类化合物的溶解度；然而，关于共溶剂对现场污染介质的有效性的数据有限。在这项工作中，我们研究了共溶剂冲洗去除前煤气厂（FMGP）土壤中多环芳烃（PAH）的效果。批处理研究证实，土壤-共溶剂分配系数（K(i)）与共溶剂体积分数（f(c)）之间的关系遵循标准的对数线性方程。使用甲醇，fc 为 0.95，在不同的长度尺度上进行了柱研究，范围从 11.9 到 110 厘米。共溶剂冲洗的孔隙体积（PV）决定了 PAH 化合物的去除。尽管使用了高 f(c)，但在所有的柱子中都观察到了速率和色谱效应。使用常见的双位点吸附模型对 PAH 流出物浓度进行了建模。通过使用 MeOH 突破曲线确定拟合的弥散系数，模型拟合得到了改善。拟合的传质速率比根据使用人工污染砂的已发表数据预测的值低两到三个数量级。
