Modeling the Adsorption of Cations in Porous Materials.

The adsorption of cations by soil particles is dependent on pH, ionic strength, and competitive ion concentrations. A remarkable recent observation also found that the adsorption is impacted by the size of the pore regions in the particle where the adsorbing ions are held. This porous environment results in very high retention of otherwise weakly held ions. More specifically, it was shown that the adsorption of Na⁺ ions can be stronger than the adsorption of Ni²⁺ ions in nanopores, but this will vary with the diameter of the pores involved. We show that this adsorption behavior can be described mathematically using competitive ion-exchange adsorption models.