Per- and poly-fluoroalkyl substances (PFAS) represent a group of pollutants extensively utilized in various industrial and commercial sectors over the past six decades. Of specific concern in this study is the utilization of Aqueous Film-Forming Foams (AFFFs) by firefighters during firefighting training exercises, which results in PFAS compounds seeping into the subsurface and drinking water supplies. The consequent contamination poses a significant health hazard to nearby communities. Adequate characterization of geochemical processes and other field-specific parameters can elucidate the understanding of PFAS sorption process and improve predictions of fate and transport models. This study presents an assessment of perfluorooctane sulfonic acid (PFOS) adsorption onto an iron-rich soil sampled from a AFFF contamination site in Killingworth, CT, 2-line ferrihydrite, Ottawa sand, and iron-coated sand. Batch adsorption experiments were performed to assess the effect of pH on PFOS adsorption, and soil-water partition coefficients (Kd) were calculated. Increased adsorption to Killingworth soil and iron-coated sand was observed at low pH values, indicating that surface charge and electrostatic interactions are significant for iron minerals and iron-rich soils. Adsorption to similar soils may affect PFOS transport at polluted sites like Killingworth, CT, especially in acidic conditions. PFOS adsorption to Ottawa sand was lower than other solid matrices at low pH values, indicating that non-electrostatic retention mechanisms may be dominant.