To successfully understand and model the environmental fate of per- and polyfluoroalkyl substances (PFAS), it is necessary to know several of their physicochemical properties (PChPs), including octanol-water partition coefficients (Kow) and acid dissociation constants (pKa). However, measured PChPs of PFAS are scarce and of uncertain reliability due to the peculiar characteristics of fluorosurfactants and the growing number and diversity of PFAS families. This makes PFAS an especially promising target for in silico methods of evaluation and estimation of PChPs. We have been developing hybrid computational methodologies that use quantum chemical methods, molecular descriptors, and Quantitative Structure-Activity Relationships (QSARs) for the estimation of PFAS PChPs. The methods represent PFAS speciation (i.e., neutral vs. ionic) and structural characteristics (e.g., carbon chain length, functional head group), and the various types of molecular interactions that PFAS might undergo in the environment (e.g., dispersion, polarizability, H-bonding). Our results show that partition coefficients—including log Kow, for anionic vs. neutral carboxylic (PFCA) acid PFAS and non-fluorinated carboxylic acid (CA) proxies—have a linear relationship and an offset that is solvent-dependent across a diverse set of solvent-water systems (selected to mimic the interactions with environmental matrices). Estimated pKa’s, using vibrational frequencies, reveal that, much like the non-fluorinated CA proxies, carbon chain length has minimal effect on the PFCA water dissociation constants.

Assessment and prediction of the physicochemical properties of per- and polyfluoroalkyl substances (PFAS) using statistical and computational chemical models

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

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