Following the global regulation of legacy PFAS molecules, fluorotelomer molecules have been widely employed as replacements to PFOS in aqueous film-forming foam (AFFF) and PFOA in other products. Recent field studies indicate that fluorotelomer molecules are increasingly identified in environmental settings including groundwater, soil and sediments. Consequently, gaining a comprehensive understanding of the fate and transport of fluorotelomers in soils and sedimentary environments is vital. In this study, the behavior of two different fluorotelomers, 6 : 2 FTS and 6 : 2 FTC, in three common soil minerals (kaolinite, montmorillonite and illite) having quite different interfacial properties are reported using molecular dynamics simulations. The interfacial adsorption and dynamical characteristics of 6 : 2 FTS and 6 : 2 FTC vary substantially between the three minerals. Irrespective of the mineral composition, 6 : 2 FTS exhibits surface complexation while 6 : 2 FTC coordinates only with neutral and low charged clay minerals. In addition, the fundamental interactions that dictate the adsorption, interfacial structure of 6 : 2 FTS and 6 : 2 FTC are completely different for the three minerals. The large, aggregated clusters of 6 : 2 FTS at the surface experienced greater stability for longer periods of time and restricted mobility than 6 : 2 FTC for all three clay minerals. Importantly, the current study provides cluster size dependent diffusion behavior of surface adsorbed fluorotelomer molecules in each clay mineral. Such detailed mechanistic insights are necessary to understand the environmental footprint of fluorotelomers around contaminated sites.

中文翻译：

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含氟调聚物与土壤矿物的界面吸附和动力学 – 机理见解


继对传统 PFAS 分子的全球监管之后，含氟调聚物分子已被广泛用作水性成膜泡沫 （AFFF） 中 PFOS 和其他产品中 PFOA 的替代品。最近的现场研究表明，含氟调聚物分子越来越多地在环境环境中被发现，包括地下水、土壤和沉积物。因此，全面了解含氟调聚物在土壤和沉积环境中的归宿和运输至关重要。在这项研究中，使用分子动力学模拟报告了两种不同的含氟调聚物 6 ： 2 FTS 和 6 ： 2 FTC 在三种具有完全不同界面特性的常见土壤矿物（高岭石、蒙脱石和伊利石）中的行为。6 ： 2 FTS 和 6 ： 2 FTC 的界面吸附和动力学特性在三种矿物之间差异很大。无论矿物成分如何，6 ： 2 FTS 都表现出表面络合，而 6 ： 2 FTC 仅与中性和低电荷粘土矿物配合。此外，决定 6 ： 2 FTS 和 6 ： 2 FTC 的吸附、界面结构的基本相互作用对于三种矿物来说是完全不同的。与所有三种粘土矿物的 6 ： 2 FTC 相比，地表的大型聚集集群在更长的时间内具有更高的稳定性和有限的流动性。重要的是，目前的研究提供了每种粘土矿物中表面吸附的含氟调聚物分子的簇大小依赖性扩散行为。这种详细的机理见解对于了解受污染场地周围含氟调聚物的环境足迹是必要的。