Efficacy of binders on sequestering per- and polyfluoroalkyl substances under in vitro ruminal conditions

The efficacy of 6 binders in sequestering perfluorooctane sulfonic acid (PFOS) under in vitro ruminal conditions was evaluated. Binders, including bentonite, montmorillonite aluminum pillared clay, chitosan, activated charcoal Norit, and cholestyramine resin (CHM), were tested at a dose of 1.8% (wt/wt; fresh basis). The PFOS (%) binding affinity of binders was calculated in relation to the control. A randomized complete block design (n = 4) was used to analyze the data. Only CHM, an anion-exchange resin, demonstrated strong potential to sequester PFOS (x_=52.5%) The binders did not affect the gas production kinetics and microbial fermentation profile parameters. Molecular dynamics simulations showed that PFOS molecules were strongly encapsulated within the CHM polymeric structure, primarily driven by interactions between the positively charged CHM and the negatively charged PFOS and stabilized by the hydrophobic interactions between the backbone of PFOS and CHM. Findings highlight the potential application of CHM in reducing PFOS contamination in livestock.