The molecular mechanisms that drive adsorption are critical for engineering new adsorbents to capture environmental contaminants, such as perfluoroalkyl substances (PFAS). Metal–organic frameworks (MOFs) have been shown to adsorb some classes of PFAS, yet a fundamental understanding of how PFAS identity and water competition affect adsorption capacity is unknown. Here, grand canonical Monte Carlo simulations of perfluoroalkanoic acids (PFAAs) adsorption in the MOF NU-1000 were performed with coadsorbed water and varying carbon chain length sizes to interrogate how PFAS structure affects adsorption capacity. We found that larger PFAAs adsorb favorably into NU-1000 than shorter chain PFAAs due to the formation of pore-filling aggregates that stabilize anionic adsorption to the node. Due to their size and hydrophilicity, shorter chains tend to limit interactions with the adsorbent. These insights offer directions for developing novel materials that promote aggregate formation to capture and retain a wider set of PFAS from aqueous solutions.

中文翻译：

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尺寸、亲水性和氟含量对 NU-1000 中全氟烷基吸附的热力学影响


驱动吸附的分子机制对于设计新的吸附剂来捕获环境污染物（例如全氟烷基物质（PFAS））至关重要。金属有机框架 (MOF) 已被证明可以吸附某些类别的 PFAS，但对 PFAS 特性和水竞争如何影响吸附能力的基本了解尚不清楚。在这里，使用共吸附水和不同的碳链长度尺寸对 MOF NU-1000 中的全氟链烷酸 (PFAA) 吸附进行了大正则蒙特卡罗模拟，以探究 PFAS 结构如何影响吸附能力。我们发现，较大的 PFAA 比较短链的 PFAA 更容易吸附到 NU-1000 中，因为形成了孔隙填充聚集体，稳定了阴离子对节点的吸附。由于其尺寸和亲水性，较短的链往往会限制与吸附剂的相互作用。这些见解为开发新型材料提供了方向，这些材料可促进聚集体形成，以从水溶液中捕获和保留更广泛的 PFAS。