Tajdini Bahareh, Vatankhah Hooman, Pezoulas Ethan R, Zhang Chuhui, Higgins Christopher P, Bellona Christopher
Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, USA.
Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, USA; Department of Civil and Environmental Engineering, Florida International University, Miami, FL, USA.
Water Res. 2025 Jan 1;268(Pt B):122774. doi: 10.1016/j.watres.2024.122774. Epub 2024 Nov 9.
The increased detection of understudied per- and polyfluoroalkyl substances (PFAS) in environmental matrices has highlighted the need to evaluate the treatability of a wide-range of PFAS by sorption-based processes. This study investigated the efficacy of three commercial adsorbents (i.e., granular activated carbon (GAC), surface modified clay (SMC), and anionic exchange resin (AER)) for the removal of a wide range of cationic, zwitterionic, and anionic PFAS from an aqueous film forming foam (AFFF)-impacted groundwater employing rapid small-scale column tests (RSSCTs) coupled with high resolution mass spectrometry (HRMS) and suspect screening analysis (SQ). AER exhibited later breakthrough times for the majority of anionic and zwitterionic PFAS compared to SMC and GAC. However, both AER and SMC exhibited negligible removal of cationic PFAS presumably due to the reliance of these adsorbents on electrostatic interactions and the counteraction of hydrophobic forces caused by the repulsion between cationic PFAS and positively charged surfaces of AER and SMC. GAC, being a non-selective adsorbent, was largely unaffected by the ionic charge of the evaluated PFAS with molecular structure having a bigger impact on adsorbability. The detection of a variety of PFAS classes in the investigated AFFF-impacted groundwater enabled assessment of the relative impact of chemical structure on adsorptive removal of PFAS. Chain-length dependent adsorption was observed across all investigated anionic and zwitterionic PFAS classes. The PFAS structures possessing hydroxyl and/or methyl functional groups exhibited later breakthrough times compared to their homologues lacking these functional groups and cyclic/unsaturated structures were removed less efficiently compared to their linear/saturated homologues. In the case of perfluoroalkyl acid (PFAA)-derivative structures, hydrogen-substituted classes (i.e., H-PFAAs) were removed more efficiency than PFAAs while keto-substituted structures (i.e., K-PFSA) and pentahydrido-fluoroalkane sulfates (PeH-FAOS) exhibited lower adsorbability compared to PFAAs for all adsorbents. Oxa-PFAAs (O-PFSA; isomer class of PFA-OS) on the other hand demonstrated higher adsorbability compared to PFAAs in the case of AER-like adsorbents, while this trend was reversed for GAC.
环境基质中对研究较少的全氟和多氟烷基物质（PFAS）检测的增加，凸显了通过基于吸附的工艺评估多种PFAS可处理性的必要性。本研究采用快速小规模柱试验（RSSCTs）结合高分辨率质谱（HRMS）和可疑物筛查分析（SQ），研究了三种商业吸附剂（即颗粒活性炭（GAC）、表面改性粘土（SMC）和阴离子交换树脂（AER））从受水成膜泡沫（AFFF）影响的地下水中去除多种阳离子、两性离子和阴离子PFAS的效果。与SMC和GAC相比，AER对大多数阴离子和两性离子PFAS表现出更晚的穿透时间。然而，AER和SMC对阳离子PFAS的去除率均可忽略不计，这可能是由于这些吸附剂依赖静电相互作用，以及阳离子PFAS与AER和SMC带正电表面之间的排斥导致疏水力的抵消。GAC作为一种非选择性吸附剂，很大程度上不受所评估PFAS离子电荷的影响，分子结构对吸附性的影响更大。在所研究的受AFFF影响的地下水中检测到多种PFAS类别，这使得能够评估化学结构对PFAS吸附去除的相对影响。在所有研究的阴离子和两性离子PFAS类别中均观察到链长依赖性吸附。与缺乏这些官能团的同系物相比，具有羟基和/或甲基官能团的PFAS结构表现出更晚的穿透时间，与线性/饱和同系物相比，环状/不饱和结构的去除效率更低。在全氟烷基酸（PFAA）衍生物结构的情况下，氢取代类（即H-PFAA）的去除效率高于PFAA，而酮取代结构（即K-PFSA）和五氢氟代烷磺酸盐（PeH-FAOS）与PFAA相比，对所有吸附剂的吸附性均较低。另一方面，对于类似AER的吸附剂，氧杂-PFAA（O-PFSA；PFA-OS的异构体类别）与PFAA相比表现出更高的吸附性，而对于GAC，这种趋势则相反。
