Remediation of water sources laden with per- and polyfluoroalkyl substances (PFAS) remains a difficult challenge due to both their lack of reactivity and their low affinity (particularly for short-chain PFAS) for traditional adsorbents such as granular activated carbon (GAC). One of the most promising technologies for PFAS remediation in groundwater are strong base ion exchange (IX) resins, which have shown promise as an effective solution for PFAS. While these resins have shown significant advantages over GAC for their treatment of PFAS, there are still limitations that need to be addressed to make this technology more cost effective. This research will look to advance the development of a novel IX resin that was previously discovered at the Johns Hopkins University Applied Physics Laboratory (JHU/APL). This proof-of-concept project will build on this bench scale technology and synthesize an improved resin bead form factor to enable future pilot scale testing.

Previous work at JHU/APL identified a group of novel, strong-base IX resins, referred to herein as Gemini resins. These resins uniquely have twin charged functional groups rigidly placed in close proximity, influencing the interaction of the resin with PFAS species and leading to multiple advantages over current state-of-the-art resins including:

• Two to five times greater adsorptive capacities for long-chain PFAS.
• Higher selectivity for short-chain PFAS when compared to a commercially available resin.
• High potential to overcome the geochemical competitors that reduce sorption media capacity during field implementation.
• Fast sorption kinetics, 10 to 50 times that of activated carbon and potentially 3 to 15 times that of commercially available resins.

While these materials have been fabricated and demonstrated at the bench scale, further research and development is required to optimize the material, with specific attention on improving the resin’s ability to be scaled and utilized in the field. The research team will conduct the following tasks:

• Develop methods to synthesize these materials into uniform beads with properties that resist fouling from natural organic matter.
• Investigate the enhanced selectivity of these resins for short-chain PFAS in order to better understand how these resins can be tailored for different competitive matrices.
• Conduct rapid small-scale column tests to compare the newly developed resin’s breakthrough capacity to commercially available resins.

If successful, this technology has the potential to significantly reduce material usage, contact time, and operational costs associated with remediation of PFAS-laden matrices. Moreover, the components and fabrication protocols associated with Gemini resins are specifically designed to be economical, setting the stage for a cost-efficient, scalable solution. In addition to these economic benefits, this work will also answer fundamental questions related to PFAS adsorption such as how does the rigid spacing of charge groups within resins affect their performance and how can resins be better tailored to attract shorter chain PFAS? (Anticipated Project Completion - 2026)