Screening of transition metals for PFAS adsorption: A comparative DFT investigation
Mohamed S. Mohamed, Brian P. Chaplin, Ahmed A. Abokifa
Abstract
• Systematic DFT investigation of PFAS adsorption on Cu, Pd, Pt, and Rh. • Influence of PFAS chain length, functional group, protonation state investigated. • Rh showed most thermodynamically favorable adsorption for PFAS. • Cu was the highest electron donor & Pt was the highest electron acceptor. Transition metals are promising candidates for catalytic destruction of per- and polyfluoroalkyl substances (PFAS). This study employed density functional theory (DFT) calculations to systematically investigate the adsorption of PFAS, which is a critical step in the catalytic process, onto a group of transition metals, namely Cu, Pd, Pt, and Rh. The investigation considered the influence of different PFAS characteristics, including chain length, functional group (i.e., sulfonic vs. carboxylic), and protonation state (i.e., protonated, anionic, and deprotonated radical) on the adsorption mechanism. Overall, the findings indicated that the adsorption of PFAS on transition metals exhibited thermodynamically favorable energetics, with Rh showing the most favorable adsorption for PFAS. However, the adsorption strength was significantly dependent on the protonation state of PFAS. Cu was the highest electron donor, while Pt was the highest electron acceptor. Results were compared to experimental studies in the literature for qualitative validation.