Description:

Abstract

The use of nanomaterials has become a rapidly growing approach for advanced water treatment technologies, but the continued emergence of highly oxidation-resistant micropollutants, such as per- and polyfluoroalkyl substances (PFAS), calls for transformative strategies that move beyond recent oxidation-based remediation practices. Alternative reduction-based approaches utilizing aqueous electrons (eaq−, Eo = −2.9 V)—one of the most reactive nucleophilic species—are emerging as a promising solution for efficient PFAS breakdown. Herein, we leverage nanoconfinement engineering to enable a new water treatment approach—plasmon-mediated advanced reduction processes (PARPs)—for efficient, chemical-free PFAS destruction at room temperature. We first present novel nanoreactor designs that engineer the ‘nanoconfinement effect’, i.e. unique aggregation-induced interparticle interactions that are inaccessible by typical unconfined, bulk-phase nanomaterials. We demonstrate that the precisely controlled nanoconfinement of plasmonic nanoparticles can generate highly reactive reducing species under UV irradiation, capable of breaking even the strong C–F bonds in PFAS. The nanoreactor we developed achieved 81.5% mineralization of perfluorooctanoic acid (PFOA) after 24 hours of UV irradiation in pure water at room temperature, compared to only 16.6% mineralization by UV photolysis. Further reaction monitoring under various conditions and multimodal NMR-guided investigation were conducted to elucidate PFAS degradation mechanisms and pathways. We further explored the potential of PARPs for the chemical-free remediation of nitrate, a prevalent oxyanion pollutant that is resistant to conventional oxidation-based treatments. Our findings highlight the transformative promise of nanoconfinement engineering to catalyze innovation in environmental nanotechnology and extend the frontier of advanced reduction processes for water treatment.

Bio- Haklae Lee is a PhD student in the Environmental Engineering & Science program and a member of the Gray Lab in the Department of Civil and Environmental Engineering at Northwestern University. He holds a B.S. and M.S. in Environmental Engineering from Pusan National University in South Korea. His work focuses on the design and engineering of nano-sized reactors for efficient and more sustainable remediation of emerging contaminants from wastewater. He uses mesoporous silica to spatially confine various metal nanoparticles within multi-layered nanoreactors, enabling unique features such as multifunctional compartments and nanoconfinement effects for previously unexplored environmental applications.