Here, we describe surface functionalized, superparamagnetic iron oxide nanocrystals (IONCs) for ultra-high PFAS sorption and precise, low energy (magnetic) separation, considering perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). As a function of surface coating, sorption capacities described are considerably higher than previous studies using activated carbon, polymers, and unmodified metal/metal oxides, among others. In particular, positively charged polyethyleneimine (PEI) coated IONCs demonstrate extreme sorption capacities for both PFOA and PFOS due to electrostatic and hydrophobic interactions, along with high polymer grafting densities, while remaining stable in water, thus maintaining available surface area. Further, through a newly developed method using a quart crystal microbalance with dissipation (QCM-D), we present real-time, interfacial observations (e.g., sorption kinetics). Through this method, we explore underpinning mechanism(s) for differential PFAS (PFOA vs PFOS) sorption behavior(s), demonstrating that PFAS functional head group strongly influence molecular orientation on/at the sorbent interface. The effects of water chemistry, including pH, ionic composition of water, and natural organic matter on sorption behavior are also evaluated and along with material (treatment) demonstration via bench-scale column studies.

在这里，我们描述了表面功能化的超顺磁性氧化铁纳米晶体 (IONC)，用于超高 PFAS 吸附和精确、低能量（磁性）分离，考虑全氟辛酸 (PFOA) 和全氟辛烷磺酸 (PFOS)。作为表面涂层的函数，所描述的吸附能力比之前使用活性炭、聚合物和未改性的金属/金属氧化物等的研究要高得多。特别是，带正电荷的聚乙烯亚胺 (PEI) 涂层 IONC 由于静电和疏水相互作用以及高聚合物接枝密度而表现出对 PFOA 和 PFOS 的极高吸附能力，同时在水中保持稳定，从而保持可用的表面积。此外，通过使用耗散石英晶体微天平（QCM-D）的新开发方法，我们提供实时的界面观察（例如吸附动力学）。通过这种方法，我们探索了不同 PFAS（PFOA 与 PFOS）吸附行为的基础机制，证明 PFAS 功能头基强烈影响吸附剂界面上的分子取向。还评估了水化学（包括 pH 值、水的离子组成和天然有机物）对吸附行为的影响，并通过小试规模的柱研究进行了材料（处理）演示。