Per‐ and polyfluoroalkyl substances (PFASs) such as PFOS and PFOA are persistent pollutants present in the subsurface at many DoD facilities, often due to the past use of aqueous film‐forming foam (AFFF) in firefighting. PFASs pose a human health threat, necessitating feasible technologies for their removal. At present, ex situ treatment of groundwater by granular activated carbon (GAC) adsorption is the most commonly used technology for treating PFAS‐contaminated water. However, this approach is very costly and relatively inefficient at removing PFOA and shorter length analogues. Ultra‐high affinity sorbents are promising for application in ex situ pump‐and‐treat adsorption systems. In addition, they offer further opportunities for in situ remedial technologies, including injection as a fine powder or use as filling in subsurface permeable adsorptive barriers.
The objective of this study is to determine the feasibility of utilizing an ultra‐high affinity sorptive remediation approach that exploits multiple, complementary bonding modes (e.g., electrostatic and hydrophobic interactions) for the remediation of PFAS‐contaminated groundwater. The innovative sorbents are cationic polyaniline (PANI) and polypyrrole (PPy) polymers containing hydrophobic moieties. The unique structure of these polymeric materials enables both strong electrostatic interaction with the functional head group of anionic PFAS and hydrophobic interactions with the fluorinated tail of PFAS, allowing them to be more selective than GAC and to adsorb a wider range of compounds than anion exchange resins. By using suitable polymer precursors, the charge density and hydrophobicity of these polymers can be tailored to enhance PFAS removal.