Surfactant solutions are commonly used for the remediation of petroleum‐contaminated soil due to their good petroleum removal performance, time‐saving capability, and cost effectiveness. However, applying surfactants in excess concentrations could make oil recovery difficult. Moreover, residual surfactants in soil are toxic to microorganisms and plants. Thus, it is crucial to identify a suitable surfactant concentration for soil washing applications. The main objective of this study was to evaluate the effect of soil minerals (quartz and kaolin) and organic matter (OM) on the critical micelle concentration (CMC) of polyethoxylated sorbitan ester surfactants (Tween 20, 40, 60, and 80) and its effect on diesel removal from diesel‐contaminated soil by soil washing. The results showed that Tween surfactants with shorter carbon chain lengths required higher CMC for diesel removal from quartz, while those with longer chains needed higher CMC for kaolin cleanup. FTIR results illustrated that oxygenated functional groups of Tween surfactants played an important role in their adsorption on quartz, while alkyl chains of Tween surfactants were responsible for their adsorption on kaolin. At a certain OM concentration, quartz and OM exhibited antagonistic effects, resulting in CMC reduction. In soil washing application, maximum diesel removal could be achieved from kaolin, in the presence of which surfactants exhibited the highest CMC. Based on FTIR results, the adsorbed surfactant could reduce the hydrophobicity of the kaolin surface, thus preventing the re‐deposition of detached diesel.

中文翻译：

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石英，高岭土和有机物对吐温表面活性剂临界胶束浓度的影响及其在柴油污染的土壤洗涤中的应用

表面活性剂解决方案具有良好的除油性能，省时能力和成本效益，因此通常用于修复石油污染的土壤。但是，使用过量浓度的表面活性剂会使采油困难。此外，土壤中残留的表面活性剂对微生物和植物有毒。因此，至关重要的是确定适合土壤洗涤应用的表面活性剂浓度。这项研究的主要目的是评估土壤矿物质（石英和高岭土）和有机物（OM）对聚乙氧基脱水山梨糖醇酯表面活性剂（吐温20、40、60和80）的临界胶束浓度（CMC）的影响，以及它对通过土壤洗涤从柴油污染的土壤中去除柴油的影响。结果表明，碳链长度较短的Tween表面活性剂需要较高的CMC才能从石英中去除柴油，而链长的表面活性剂需要较高的CMC来净化高岭土。FTIR结果表明，吐温表面活性剂的氧化官能团在其吸附石英上起重要作用，而吐温表面活性剂的烷基链是其在高岭土上吸附的原因。在一定的OM浓度下，石英和OM表现出拮抗作用，导致CMC降低。在土壤洗涤应用中，在高岭土的存在下，表面活性剂表现出最高的CMC，可以最大程度地去除柴油。根据FTIR结果，吸附的表面活性剂可以降低高岭土表面的疏水性，从而防止分离的柴油再沉积。