Per-and Polyfluoroalkyl Substances(PFAS) are a class of ubiquitous and highly-persistent fluoro-organic water contaminants within the environment that have been widely utilized since the 1960’s. They are utilized in numerous industrial applications as surfactants, and are found in products such as firefighting foams, makeup, nonstick cookware, waterproof fabrics, and plastics. The most common PFAS compound in the environment today is perfluorooctanoic acid (PFOA), and exposure to PFOA has been correlated to an increased risk of thyroid conditions and certain types of cancers. The current most common resin material used to separate PFOA from water is activated carbon, which lacks the hydrophobicity necessary to be an efficient anion exchange resin to effectively adsorb the hydrophobic PFOA. As a result, an economical and effective adsorption technique to remediate PFAS-contaminated water is in great demand. The goal of this experiment is to synthesize a novel fluorinated hydrocarbon anion exchange resin for the adsorption of PFOA. The resin was synthesized by grafting the fluoropolymer ethylene-chlorotrifluoroethylene (Halar) to activated carbon in differing ratios, and then reacting with the amine polymer polyethylenimine (PEI) in a 1:1 Halar:PEI ratio. Resins were then evaluated by HPLC to determine optimal reaction conditions. Reaction novelty was evaluated by attenuated total reflectance infrared spectroscopy , F19 Nuclear Magnetic Resonance, and Scanning Electron Microscopy. Analysis of surface effects were performed via zeta-potential analysis and SEM. We found that a 5:2 AC-Halar-PEI resin was the optimal reaction condition, with a PFOA breakthrough time approximately 300% longer than activated carbon. Zeta potential analysis indicated higher anion-exchange effects than activated carbon, and BET surface area analysis by SEM indicated a decrease in pore size in resin synthesis from 372 m^2/g in activated carbon to 122 m^2/g in 5:2 AC-Halar-PEI Future work involving this resin will examine the grafting mechanism between activated carbon and Halar, as well as reaction conditions to further react the AC-Halar intermediate with unreacted amine groups in PEI to generate a multilayer sorbent. This study helped generate important insights into the synthesis of economic materials that can potentially be utilized to remediate widespread and persistent ecological contaminants.
Author(s): Matthew Beckman, Chemistry Major
Advisor(s): Neil Danielson, Department of Chemistry and Biochemistry
Charles Xie, Department of Chemistry and Biochemistry
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