Researchers at Arizona State University (led by Bruce Rittmann of the Biodesign Swette Center for Environmental Biotechnology), with collaborators from Rice University, Tongji University, the National University of Singapore, and Nanjing University, developed a catalytic “hunter- killer” membrane that both captures and chemically destroys PFAS (“forever chemicals”) rather than just concentrating them.

PFAS are synthetic compounds used in nonstick coatings, waterproof fabrics, firefighting foams, and many other products. Their extreme persistence comes from very strong carbon- fluorine bonds (often called the strongest in organic chemistry), which shield the carbon backbone and resist breakdown by conventional biological or chemical processes. Standard treatments (activated carbon, ion exchange, membrane filtration) remove them from water but leave concentrated waste that still needs disposal or destruction.

How the technology works

• Hollow- fiber membranes are coated on the outside with palladium nanoparticles.
• Pressurized hydrogen gas is fed through the interior of the fibers and diffuses outward to the palladium catalyst.
• The palladium splits H₂ into highly reactive hydrogen atoms.
• PFAS molecules from the surrounding water adsorb onto the same palladium surface.
• At the catalyst surface, the reactive hydrogen attacks and breaks the C- F bonds (hydrodefluorination), stripping fluorine and converting the persistent molecules into less harmful components.

This “inside- out” hydrogen delivery is a key design feature: the membrane both concentrates the pollutants at the reactive surface and supplies the activated hydrogen needed to dismantle them.

Performance results

In a continuous 58- day laboratory test treating a mixture of six regulated- priority PFAS compounds, the system removed more than 90% of each compound and stripped away about 83% of the total fluorine, confirming actual chemical destruction rather than simple filtration. Rittmann described the mechanism as essentially universal across the six compounds tested.

Practical considerations and next steps

Palladium is expensive (roughly $50,000 per kilogram), so reducing catalyst loading is a major research priority. The approach is envisioned as a complement to existing concentration methods: conventional filtration would first shrink large volumes of contaminated water into a smaller waste stream that the catalytic membrane then destroys. Hybrid systems pairing the palladium catalyst with pollutant- degrading bacteria are also under development.⁠

This builds on earlier ASU work with membrane biofilm reactors (MBfR) and membrane catalyst- film reactors (MCfR) that combine catalytic defluorination with microbial degradation. While further engineering is needed for full- scale water treatment, the results demonstrate a promising route to permanently break down these persistent pollutants.

The membrane technology developed by Arizona State University researchers (led by Bruce Rittmann) and international collaborators is a catalytic hollow- fiber membrane system designed to both capture and chemically destroy PFAS (“forever chemicals”).

Core design

• Hollow- fiber membranes: Tiny tubular (“straw-like”) gas- transfer membranes.
• Palladium nanoparticle coating: A thin layer of palladium nanoparticles is deposited on the outside of the fibers. Palladium acts as a catalyst.
• Hydrogen delivery: Pressurized hydrogen gas (H₂) is fed through the inside of the hollow fibers. It diffuses outward through the membrane wall to the palladium layer.

How it works (“hunter- killer” mechanism)

1. Hydrogen reaches the palladium surface and is split into highly reactive atomic hydrogen.
2. PFAS molecules in the surrounding water adsorb onto the same palladium surface.
3. At the catalyst surface the reactive hydrogen attacks the strong carbon- fluorine bonds (hydrodefluorination), stripping fluorine atoms from the PFAS molecules.
4. This breaks the “forever” chemical structure, converting the compounds into less persistent (and ultimately more biodegradable) products.

The inside- out hydrogen supply is a key innovation: the membrane simultaneously concentrates the pollutants at the reactive surface and delivers the activated hydrogen needed to destroy them.

Performance

In a continuous 58- day laboratory trial treating a mixture of six regulated- priority PFAS compounds, the system:

• Removed >90% of each individual PFAS.
• Stripped ~83% of the total fluorine (confirming actual chemical destruction rather than mere capture).

Context and next steps

This builds on earlier ASU membrane technologies (Membrane Biofilm Reactor- MBfR and Membrane Catalyst- film Reactor- MCfR). Hybrid versions that combine the palladium catalyst with pollutant-degrading bacteria are also under development.

Main practical hurdle: Palladium is expensive (~$50,000/kg), so reducing catalyst loading is a priority. The technology is expected to work best as a polishing/destruction step after conventional concentration methods (e.g., activated carbon or ion exchange) have first reduced the volume of contaminated water.

The research was published in the Proceedings of the National Academy of Sciences in October 2026.

Catalytic reactive-hydrogen membranes for rapid capture and hydrodefluorination of six PFAS of regulatory concern

This peer- reviewed paper reports the development and continuous testing of a hydrogen- based Membrane Catalyst -film Reactor (MCfR) for simultaneous capture and destruction of PFAS (“forever chemicals”).

It reports the development and continuous testing of a hydrogen- based Membrane Catalyst- film Reactor (MCfR) for simultaneous capture and destruction of PFAS (“forever chemicals”).

Key elements of the paper (from published summaries)

• Lead institution & author: Arizona State University’s Biodesign Swette Center for Environmental Biotechnology; senior/corresponding author Bruce E. Rittmann.
• Collaborators: Researchers from Rice University (Texas), Tongji University (China), National University of Singapore, and Nanjing University (China).
• Technology: Hollow- fiber gas- transfer membranes coated on the exterior with palladium (Pd) nanoparticles. Hydrogen gas is supplied from the lumen (inside) of the fibers, diffuses outward, and is activated on the Pd surface. PFAS molecules adsorb to the same surface, enabling catalytic hydrodefluorination (breaking of strong C- F bonds by reactive hydrogen).
• Results: In a continuous 58- day operation treating a mixture of six regulatory-priority PFAS compounds, the system achieved >90% removal of each compound and ~83% overall fluorine removal (defluorination), confirming chemical destruction rather than simple separation.
• Significance: Demonstrates a “universal” catalytic mechanism effective across the tested PFAS. The approach is positioned to treat concentrated waste streams after conventional separation processes. Palladium cost and catalyst loading reduction are noted as practical challenges; hybrid Pd–microbial systems are also referenced as ongoing work.

This builds on the group’s earlier Membrane Catalyst- film Reactor (MCfR) platform for catalytic reduction of oxidized contaminants using efficient H₂ delivery.

Direct full- text access may require institutional login or purchase via the PNAS site, as the open-page retrieval was restricted. The news coverage from ASU- affiliated and science outlets (e.g., Eurasia Review, Interesting Engineering, Bioengineer.org) provides consistent, detailed summaries of the findings.

Journal: Proceedings of the National Academy of Sciences

DOI: 10.1073/pnas.2613985123

Provided: Arizona State University

Authors: Min Long, Ai-Shi Wangh, Welman C. Elias,, Thomas P. Senftle, Michael S. Wong, Jie Cheng and Bruce E. Rittmann

Abstract

Per- and polyfluoroalkyl substances (PFAS) persist in aquatic environments due to their ultrastable C–F bonds and poor susceptibility to conventional treatment. Here, we report an H₂-based catalytic-film membrane that enables PFAS destruction in ambient conditions by generating highly reactive surface (H_ads^*) and subsurface hydrogen (H_sub^*), the latter stored as β-phase palladium hydride (β-PdHx). Solid-state analyses evidenced β-PdHx formation and related lattice expansion with elevated H₂ chemical potential, revealing a structural mechanism that links hydrogen storage to catalytic defluorination. Mechanistically, the two hydrogen species play complementary roles: H_ads^*-rich Pd⁰ surface enabled PFAS capture through parallel adsorption to maximize interfacial contact with active H, whereas sustained H_sub^* supplied the energetic driving force for stepwise hydrodefluorination consistent with sequential C–F scission. As a result, across six PFAS of regulatory concern—PFOA, PFOS, PFNA, PFHxS, PFBS, and GenX—the catalytic membrane converted all contaminants toward fully defluorinated products. Long-chain PFAS were removed and defluorinated more rapidly than short-chain analogs, while GenX showed greater recalcitrance due to its ether linkage, weaker adsorption, and higher average C–F bond dissociation energy; nonetheless, GenX still exhibited removal and defluorination, with the production of 2-propoxypropanoic acid. The system also enabled continuous coremoval of all six PFAS in ambient conditions, with up to 96% removal and 83% defluorination over 58 d. These findings provide a mechanistic framework for how active hydrogen is generated, stored, and deployed in catalytic membranes, and identify engineered H₂-catalytic membranes as a promising low-energy technology for destructive PFAS treatment.