Condensed-phase Hydrolysis of Per- and Polyfluoroalkyl Substances (PFAS)
EMMA D'AMBRO, Benjamin Murphy, Ivan Piletic, Havala Pye, Jesse Bash, US Environmental Protection Agency
Abstract Number: 352
Working Group: Chemicals of Emerging Concern in Indoor and Outdoor Aerosol: Sources, Vectors, Reactivity, and Impacts
Abstract
Per- and polyfluoroalkyl substances (PFAS) are a class of thousands of industrially-produced compounds that have been released into the environment for decades. They are often long-lived, resulting in their distribution throughout the globe in all environmental media, and earning them the nickname “forever chemicals”. Despite their nickname, several atmospheric chemical transformations have been documented, and as our understanding of the present and historical atmospheric emissions of PFAS grows, so too does our understanding of important atmospheric chemical pathways. One such pathway is the hydrolysis of acyl fluoride-containing compounds into carboxylic acid-containing compounds. The hydrolysis of acyl fluorides to carboxylic acids is rapid in bulk condensed water, and the resulting carboxylic acids exhibit higher solubility in atmospheric particles resulting in decreased atmospheric lifetimes due to enhanced deposition. This process is relevant for one compound of particular regulatory and public interest: HFPO-DA (GenX). We apply the Community Multiscale Air Quality (CMAQ) model version 5.4 to a case study in Eastern North Carolina to model the PFAS emissions, transport, and chemical transformations at fine scale (1 km) from the Chemours Inc. Fayetteville-Works facility. We implement condensed-phase hydrolysis of hexafluoropropylene dimer acyl fluoride (HFPO-DAF) to hexafluoropropylene dimer acid (HFPO-DA) in aerosol and cloud liquid water. We evaluate the model’s deposition predictions with deposition measurements in North Carolina and discuss the impact of this chemical transformation on results.
Disclaimer: The views expressed in this presentation are those of the authors and do not necessarily reflect the views or policies of the U.S. EPA.