View the original post from the John and Marcia Price College of Engineering here.

A massive, worldwide effort is underway to remove a class of toxic pollutants known as PFAS, short for Per- and polyfluoroalkyl substances, from the environment.  The U.S. Environmental Protection Agency has recently issued a drinking water regulation banning six such PFAS.

These fluorine-based compounds have been ubiquitous in industrial applications and consumer products for decades, thanks to their toughness and impermeability. The qualities that made them ideal for scratch-resistant coatings, waterproofing seals and fire-fighting foam now make them perniciously difficult to get rid of, earning them the moniker “forever chemicals.”

Although many PFAS compounds have been banned, the effort to clean up existing contamination demands extensive R&D for both detection and remediation. The new EPA regulation earmarks up to $1 billion for such efforts.

Research from the University of Utah’s John and Marcia Price College of Engineering and College of Science has introduced a new tool in this fight: a material that fluoresces as it absorbs PFAS.

Published in the journal ACS Applied Materials & Interfaces, the industry-funded study demonstrates the efficacy of the researcher’s new porous material, a metal-organic framework (MOF) that they have dubbed “U-1.” The research was conducted by Ling Zang, a professor in the Department of Materials Science and Engineering, Rana Dalapati, a postdoctoral researcher in Zang’s lab, and others.

Many existing chemicals and compounds readily bind to PFAS chemicals, either neutralizing their biological toxicity or allowing them to be more easily skimmed off contaminated water supplies. The latter type, known as sorbents, is part of the typical approach water treatment plants use to eliminate PFAS.

Such approaches, however, have limitations.

“While these materials, like granular activated carbon, are capable of removing PFAS from water,” Zang said, “they give no indication of the actual quantity of PFAS captured, including whether any is captured at all.”

“This uncertainty is a significant challenge, especially for water treatment facilities and remediation sites, as it is impossible to know exactly when these sorbents become saturated,” he said. “Once saturation is reached, a significant amount of PFAS could bypass the system untreated before fresh sorbent is added.”

Measuring the concentration of PFAS in a water sample is something that is typically done in a laboratory and is too slow to address the water treatment problem.

“As such,” Dalapati said, “there have been multiple attempts at designing molecules that can both adsorb PFAS and give a signal that it has done so.”

The researchers’ U-1 material is an improvement, thanks to its novel design. Earlier fluorescent MOF sorbents worked by starting in an “on” state; binding to a PFAS molecule would then break the fluorescent component of the MOF, turning it off.

“While effective in laboratory setting,” Dalapati said, “in practice, the background noise and false positives of the MOFs turning off prematurely made them unreliable.”

The design reported in Zang and Dalapati’s new paper works in reverse, with U-1’s fluorescence being turned on by the binding of PFAS. This approach provides a much more consistent signal; when the fluorescence in the contaminated water stabilizes, it means that the supply of U-1 has been used up—or that no more PFAS remains.

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Fluorescence Turn-on Detection of Perfluorooctanoic Acid (PFOA) by Perylene Diimide-Based Metal-Organic Framework; authors: Rana Dalapati, Matthew Hunter, Mostakim S.K., Xiaomei Yang and Ling Zang; published in ACS Applied Materials & Interfaces

This research was sponsored by Gentex Corp. under award #10060686. U-1 technology was developed as part of a collaboration between Ling Zang’s lab at the University of Utah and Gentex Corp., a Michigan-based technology company on whose board of directors Zang sits. The university’s Technology Licensing Office and Gentex are undergoing conversations for future collaboration and commercialization of U-1.

• Evan Lerner Director of communications, John and Marcia Price College of Engineering
  801-581-5911 evan.lerner@utah.edu