14 May 2024

Properties and Mechanisms for PFAS Adsorption to Aqueous Clay and Humic Soil Components

Abstract: The proliferation of poly- and perfluorinated alkyl substances (PFASs) has resulted in global concerns over contamination and bioaccumulation. PFAS compounds tend to remain in the environment indefinitely, and research is needed to elucidate the ultimate fate of these molecules. We have investigated the model humic substance and model clay surfaces as a potential environmental sink for the adsorption and retention of three representative PFAS molecules with varying chain length and head groups. Utilizing molecular dynamics simulation, we quantify the ability of pyrophyllite and the humic substance to favorably adsorb these PFAS molecules from aqueous solution. We have observed that the hydrophobic nature of the pyrophyllite surface makes the material well suited for the sorption of medium- and long-tail PFAS moieties. Similarly, we find a preference for the formation of a monolayer on the surface for long-chain PFAS molecules at high concentration. Furthermore, we discussed trends in the adsorption mechanisms for the fate and transport of these compounds, as well as potential approaches for their environmental remediation.

22 Feb 2024

2D Fluorinated Graphene Oxide (FGO)-Polyethyleneimine (PEI) Based 3D Porous Nanoplatform for Effective Removal of Forever Toxic Chemicals, Pharmaceutical Toxins, and Waterborne Pathogens from Environmental Water Samples

Abstract: Although water is essential for life, as per the United Nations, around 2 billion people in this world lack access to safely managed drinking water services at home. Herein we report the development of a two-dimensional (2D) fluorinated graphene oxide (FGO) and polyethylenimine (PEI) based three-dimensional (3D) porous nanoplatform for the effective removal of polyfluoroalkyl substances (PFAS), pharmaceutical toxins, and waterborne pathogens from contaminated water. Experimental data show that the FGO-PEI based nanoplatform has an estimated adsorption capacity (qm) of ∼219 mg g−1 for perfluorononanoic acid (PFNA) and can be used for 99% removal of several short- and long-chain PFAS. A comparative PFNA capturing study using different types of nanoplatforms indicates that the qm value is in the order FGO-PEI > FGO > GO-PEI, which indicates that fluorophilic, electrostatic, and hydrophobic interactions play important roles for the removal of PFAS. Reported data show that the FGO-PEI based nanoplatform has a capability for 100% removal of moxifloxacin antibiotics with an estimated qm of ∼299 mg g−1. Furthermore, because the pore size of the nanoplatform is much smaller than the size of pathogens, it has a capability for 100% removal of Salmonella and Escherichia coli from water. Moreover, reported data show around 96% removal of PFAS, pharmaceutical toxins, and pathogens simultaneously from spiked river, lake, and tap water samples using the nanoplatform.

20 Nov 2023

Internal Standard and Deuterated Solvent Selection: A Crucial Step in PFAS-based Fluorine-19 (¹⁹F) NMR Research

Purpose: This work is vital because it provides researchers with a framework and rationale for selecting the best internal standard and deuterated solvent for their nuclear magnetic resonance (NMR) analysis of per- and polyfluoroalkyl substances (PFAS)-based compounds. Selecting the best internal standard and deuterated solvent will help to ensure that their results are accurate, precise, and sensitive. The internal standard that is chosen can significantly affect the accuracy, precision, sensitivity, and quantification of NMR measurements. Therefore, it is essential to carefully select an internal standard and a matching deuterated solvent that are well-suited for analyzing PFAS compounds.

31 May 2023

Extraction and Analysis of Per- and Polyfluoroalkyl Substances (PFAS) from Meals Ready-to-Eat (MRE) Films Using GC-MS and LC-MS/MS

OBJECTIVE: This work was in response to the Defense Logistic Agency’s (DLA) Subsistence Network Broad Agency Announcement, BAA-0003-16 addressing 2019 NDAA Section 329 that states packaging materials used for Meals Ready-to-Eat (MRE) that contact food products must be free of per- and polyfluoroalkyl substances (PFAS). This was addressed by determining the presence or absence of PFAS on MREs by extraction followed by gas chromatography mass spectrometry (GC-MS) and liquid chromatography tandem mass spectrometry (LC-MS/MS). Any samples positive for PFAS were quantitated using LC triple quadrupole (QqQ) MS at the US Army Engineering and Research Development Center (ERDC) and by high resolution quadrupole time-of-flight (qTOF) MS and GC-MS at Oregon State University (OSU).

1 Oct 2020

Optimization of LC-MS/MS Parameters for Analysis of Per- and Polyfluoroalkyl Substances (PFAS)

Purpose: Integrate US Environmental Protection Agency (USEPA) Method 537 on current instrumentation to provide per- and polyfluoroalkyl substances (PFAS) analytical capabilities for the US Army Engineer Research and Development Center (ERDC), US Army Corps of Engineers (USACE) and the Department of Defense (DoD).