Mass Transfer Studies in Sorbing Porous Media I. Analytical Solutions

Abstract An analytical solution is presented for the movement of chemicals through a sorbing porous medium with lateral or intra‐aggregate diffusion. The liquid phase in the porous medium is divided into mobile and immobile regions. Diffusional transfer between the two liquid regions is assumed to be proportional to the concentration difference between the mobile and immobile liquids. Sorption processes in both the dynamic and stagnant regions of the medium are assumed to be instantaneous and the adsorption isotherm is assumed to be linear. The analytical model derived here describes the extensive tailing observed during flow through an unsaturated, aggregated sorbing medium and explains the often observed early breakthrough of chemicals in the effluent.