Per- and polyfluoroalkyl substances (PFAS) are highly persistent, bioaccumulative, and toxic contaminants that are ubiquitous at trace levels in many environmental matrices, including surface water and drinking water. Conventional water treatment strategies are ineffective against PFAS or are expensive, so novel remediation approaches are required. Reduction of PFAS with the hydrated electron has been well-studied but is prohibitively slow and inhibited by interferences, since PFAS concentrations are low relative to more reactive species in the matrix.  To overcome the limitations of a reduction-only remediation strategy, we investigated the feasibility of preceding reduction with a concentration step. Concentration was performed either by sorption to carbon nanotubes or by aerosolization. In the case of concentration via sorption, four PFAS species were investigated (PFOA, PFOS, PFBS, and GenX). Hydrated electrons were generated via the UV irradiation of sulfite. It was found that reduction only occurred when PFAS was not sorbed and this could be described using a combined kinetics sorption model. Liquid chromatography coupled to high-resolution mass-spectrometry was performed and a nontarget analysis approach was used to identify PFAS reductive transformation products. We found that in some cases the transformation product distribution was affected by the presence of CNTs, but the molecular formulas of transformation products detected were not. Furthermore, we identified novel unsaturated perfluorosulfonate products not previously described in the PFAS-hydrated electron literature and propose several possible reaction mechanisms for their formation. Our results suggest that a treatment train approach involving concentration then reduction is a promising path forward to tackling the ubiquitous challenge of PFAS contamination in drinking water.

Effect of pre-concentration by sorption or aerosolization on the transformation products from UV/sulfite reduction of per- and polyfluoroalkyl substances

ACS Spring 2022

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