“…Characterizing the adsorption of PFAS for a wide variety of adsorbents and delineating associated adsorption mechanisms has been a major focus of research for more than the past decade, as reviewed by Du et al (2014). The transport of sorbing solutes can be influenced by nonlinear and rate-limited adsorption, and prior research has demonstrated this behavior for the transport of hydrocarbon surfactants (e.g., Adeel and Luthy, 1995;Hayworth and Burris, 1997;Smith et al, 1997;Noordman et al, 2000) and for PFAS (Lyu et al, 2018;Lv et al, 2018;Brusseau et al, 2019aBrusseau et al, , 2019b. In addition, it is well established that the transport of solutes in unsaturated porous media can be influenced by the presence of poorly-advective domains associated with water trapped in drained and dead-end pores, with preferential flow and rate-limited diffusive mass transfer contributing to nonideal transport (e.g., Selim and Ma, 1998).…”