Pollutant transfer in water-bearing strata with accounting for two-site adsorption

We consider the problem of pollutant transfer in a porous medium consisting of two zones (with moving and motionless water) taking into account convective transfer, hydrodynamic dispersion, two-site adsorption, and internal diffusive mass transfer between the two zones. Basing on a numerical solution to the problem, we determine the distribution of concentration of the substance in the moving water zone, the amount of the adsorbed substance (nonequilibirum, equilibrium, and general), and internal diffusive mass transfer for various combinations of non-equilibirum and equilibrium adsorption. Along with linear kinetics, we study the nonlinear kinetics of adsorption and internal diffusive mass transfer. We establish that with the growing share of non-equilibirum adsorption the rate and total amount of the adsorbed substance decrease, which leads to preceding advance of concentration profiles in the porous medium. In case the conditions are preserved, passage to nonlinear kinetics strengthens adsorption and internal diffusive mass transfer.