Mata-Sandoval Juan C, Karns Jeffrey, Torrents Alba
Department of Civil and Environmental Engineering University of Maryland at College Park, 20742, USA.
Environ Sci Technol. 2002 Nov 1;36(21):4669-75. doi: 10.1021/es011260z.
A rhamnolipid biosurfactant mixture produced by P. aeruginosa UG2 and the surfactant Triton X-100 were tested for their effectiveness of enhancing the desorption of trifluralin, atrazine, and coumaphos from soils. Sorption of both surfactants by the soils was significant and adequately described by the Langmuir-type isotherm. Values of maximum sorption capacity (Qmax) and Langmuir constant (Klang) did not correlate with the amount of soil organic matter. Our results indicate that clay surfaces play an important role in the sorption of surfactants. When surfactant dosages were high enough to reach soil saturation and maintain an aqueous micellar phase, pesticide desorption was only enhanced. At dosages below soil saturation, surfactants sorbed onto soil, increasing its hydrophobicity and enhancing the sorption of the pesticides by a factor of 2. Similar values of water-soil partition coefficients (Ksol*) for aged and fresh added pesticides to soils indicate that the aging process used did not significantly after the capability of either surfactant to desorb the pesticides. A model able to estimate equilibrium distributions of organic compounds in soil-aqueous-micellar systems was tested against experimental results. The determined organic carbon partition coefficients, Koc values, indicate that, on a carbon normalized basis, sorbed Rh-mix is a much better sorbent of pesticides than TX-100 or soil organic matter. These results have significant implications on determining the effectiveness of surfactants to aid soil remediation technologies.
对铜绿假单胞菌UG2产生的鼠李糖脂生物表面活性剂混合物和表面活性剂吐温X-100增强氟乐灵、阿特拉津和蝇毒磷从土壤中解吸的效果进行了测试。两种表面活性剂在土壤中的吸附作用显著，可用朗缪尔型等温线充分描述。最大吸附容量（Qmax）和朗缪尔常数（Klang）的值与土壤有机质含量无关。我们的结果表明，粘土表面在表面活性剂的吸附中起重要作用。当表面活性剂剂量足够高以达到土壤饱和并维持水相胶束相时，农药解吸仅得到增强。在低于土壤饱和的剂量下，表面活性剂吸附到土壤上，增加了土壤的疏水性，并使农药的吸附增强了2倍。老化农药和新添加到土壤中的农药的水土分配系数（Ksol*）相似，表明所用的老化过程对任何一种表面活性剂解吸农药的能力没有显著影响。针对实验结果测试了一个能够估算有机化合物在土壤-水-胶束系统中平衡分布的模型。测定的有机碳分配系数Koc值表明，在碳归一化基础上，吸附的鼠李糖脂混合物比吐温X-100或土壤有机质对农药的吸附能力强得多。这些结果对确定表面活性剂辅助土壤修复技术的有效性具有重要意义。
