This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Ask a chemist to name the strongest single bond in organic chemistry, and they'll likely say carbon-fluorine. It's that bond, repeated dozens of times over, that gives per- and polyfluoroalkyl substances (PFAS) their nickname: forever chemicals.
Manufacturers prize PFAS for the same reason regulators dread them. The bonds barely break down, which is exactly why the compounds are so good at repelling water, oil and heat in everything from semiconductor fabrication to nonstick cookware. This is also why PFAS persist in soil, water and living tissue long after serving their industrial purpose.
Susanna Maisto, a fifth-year Ph.D. student in Professor John Fortner's lab in the Department of Chemical & Environmental Engineering at Yale University, has focused her doctorate on finding a way to remove PFAS at their source, called point-source treatment, by re-engineering the molecules themselves. She defended her research, titled "Esterification as a Novel Treatment Paradigm for Aqueous Perfluorocarboxylic Acids," on July 24. Most industrial approaches to PFAS treat the pollutant as something to be caught: activated carbon adsorbs it, and reverse osmosis filters it out.
Both methods pose considerable expense, and neither actually destroys PFAS. Maisto's approach instead changes the chemistry of the molecule itself. Her method uses a reaction with octanol (a chemical cousin of ordinary alcohol) that latches onto a PFAS molecule and roughly doubles its size.
The larger molecule is no longer soluble in water, so it separates out on its own. And the same reaction that makes it insoluble also makes it dramatically easier to destroy, turning what used to be two separate treatment problems into one. The trick lies in getting an organic reaction to happen in water at all, something organic chemistry generally can't do.
Maisto adapted a technique first described by chemists at the University of Tokyo in 2002, which emulsifies the PFAS into tiny droplets suspended in the aqueous phase. Those droplets effectively act as microreactors, giving the octanol and PFAS a place to react that ordinary open water wouldn't allow. The approach works across a broad range of PFAS chemistries, including newer replacement compounds that have proven especially resistant to existing treatment methods.
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