Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Environ Sci Technol. 2010 May 15;44(10):3677-82. doi: 10.1021/es9034705.
To achieve a higher efficiency of thermal remediation of soil contaminated with organic compounds, the retention mechanisms of organic compounds on thermally treated soil need to be understood adequately. In this study, a soil-column gas chromatography approach was developed to determine the soil-air partition coefficients (K(SA)) at 300 degrees C for a diverse set of nonionic organic compounds bearing many different functional groups; and the retention mechanisms of these organic compounds on two typical soils, isohumisols and ferralisols, were characterized using a polyparameter linear free energy relationship (pp-LFER). The K(SA) values (mL g(-1)) of typical volatile organic compounds (VOCs) with lower boiling points were <1.5 and in some cases even below 1.0, suggesting the rapid removal of VOCs from soils at 300 degrees C. Moreover, the K(SA) values were found to be a strong function of the soil-column temperature T (K), and be almost independent of the carrier-gas flow rate. Significant differences in molecular interactions were noted among various soil-solute pairs. The relative contributions of nonspecific van der Waals forces to the retention of test polar solutes were higher on isohumisols than on ferralisols. In contrast to the reported pp-LFER models for natural soils and soil components at normal environmental temperatures, our results suggest that elevated temperature remarkably reduces H-bond interactions between polar organic compounds and the soil matrix, thus allowing accelerated desorption of polar organic compounds from soils during thermal treatment.
为了提高受有机物污染土壤的热修复效率，需要充分理解有机物在热处理土壤上的保留机制。本研究开发了一种土壤柱气相色谱法，以确定在 300°C 下具有许多不同官能团的各种非离子有机化合物的土壤-空气分配系数（K(SA)）；并使用多参数线性自由能关系（pp-LFER）对这些有机化合物在两种典型土壤（淋溶土和铁铝土）上的保留机制进行了表征。典型挥发性有机化合物（VOCs）的 K(SA)值（mL g(-1)）较低，沸点较低的<1.5，在某些情况下甚至低于 1.0，这表明 300°C 时 VOCs 可从土壤中迅速去除。此外，K(SA)值强烈依赖于土壤柱温度 T（K），几乎与载气流速无关。不同土壤-溶质对之间存在显著的分子相互作用差异。与正常环境温度下天然土壤和土壤成分的报告 pp-LFER 模型相比，我们的结果表明，升高温度会显著降低极性溶质与土壤基质之间的氢键相互作用，从而允许在热修复过程中加速极性有机化合物从土壤中的解吸。
