Per- and polyfluoroalkyl substances (PFAS), a group of persistent, pervasive, and toxic recalcitrant contaminants, were recently detected in different surface water resources worldwide. Currently, adsorption, which only temporarily sequesters PFAS, is the only method for PFAS remediation, and more efficient destructive technologies are desired. The strong C-F bond makes them hard to be broken down through chemical biological degradation processes, and so efficient water treatment technologies are urgently demanded. We previously discovered that commercial hexagonal boron nitride (BN) photocatalytically degraded perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) under UV-C (254 nm) illumination using air as oxidant1,2. In the present work, I will present follow-up work which extended the wavelength range of the reactivity into the UV-A (365nm light) regime by simply synthesizing BN/TiO2 composite via calcination for PFAS degradation. PFOA was studied as the PFAS model compound. BN/TiO2 showed ~15x faster reactivity than TiO2 according to the PFOA half-lives, while BN was non-active. To understand the unique activity of BN/TiO2, band diagram analysis will be presented with the assistance of spectroscopy characterizations. A reaction mechanism describing the PFOA degradation will also be discussed according to EPR and radical scavenging experiment results. I will show the PFOA degradation results in salt-containing model water under Houston sunlight. This work presents an effective PFAS destruction approach using a photocatalyst comprised of earth-abundant elements.

Boron nitride/titanium dioxide heterojunction photocatalytically degrades perfluorooctanoic acid under Ultraviolet-A

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.