A molecular dynamics investigation into manipulating graphene flake spacing for increased selectivity towards short...

Per- and polyfluoroalkyl substances (PFAS) are environmentally persistent contaminants that are often referred to as "Forever Chemicals". They are used in industrial and household products; however, they are resistant to degradation. Thus, PFAS contamination has become a wide-spread issue. In 2024, the EPA announced two rules regarding PFAS limiting the level of five PFAS in drinking water, and classifying PFOA and PFOS as hazardous chemicals. Adsorbent materials will be crucial to address up-concentration and removal of these species from our waterways. In our previous work, we examined five functionalized graphene flakes for PFAS capture and found that adsorption was dependent on flake clustering and functional group. Graphene oxide showed promise because the flakes generated pseudo-porous pockets. Herein, we report a new modeled material obtained by adding hydrophobic alkyl chains to graphene oxide in order to determine the impact the chains have on flake clustering and PFAS adsorption. We found that adding alkyl chains increases the propensity of capture for PFBA, a small chain PFAS that is notoriously difficult to capture. Radial distribution functions showed a large preference for PFBA and PFOA over PFOS adsorption, which is the opposite of what is typically seen in the literature for most other sorbents.