Interaction of ADONA with neutral and charged clay interfaces: molecular insights

Abstract

Ether-based per- and polyfluorinated alkyl substances (PFAS) are increasingly used as alternatives to legacy PFAS due to their higher tendency to break down in natural settings. Among these, ADONA – a carboxylate ether-PFAS replacement species – is a prominent substitute for PFOA. However, despite its intended decrease in toxicological behavior, ADONA has been associated with some adverse effects in biological systems and is considered an emerging contaminant. Subsequent to employing ADONA for nearly two decades, these molecules are increasingly detected in environmental matrices, particularly near industrial sites. Consequently, there is an increased risk for human exposure through water sources. At the same time, soil minerals could play a central role in governing the leaching of ADONA from surface environments to groundwater. In this study, the influence of soil mineral components on the distribution and transport of ADONA in terrestrial environments has been investigated using molecular dynamics (MD) simulations. Three common clay minerals were chosen as models due to their distinct variations in both charge distribution and magnitude at their basal surfaces. The interfacial adsorption structures and dynamic properties of ADONA vary substantially between different mineral surfaces, and the adsorption mechanism strongly depends on the surface charge of the minerals examined.