An Ion-solvation Type Approach to Cation-Soil Binding Interaction: Analysis of Thermodynamic Data

The overall thermodynamic parameters for exchange of Ca²⁺ and K⁺ between water and different soils have been split into a number of components to understand the thermodynamics of the binding interactions of the cations in the soil phase alone. For this purpose, the exchange process has been conceptually considered to be equivalent to the working of a galvanic cell. The coulombic contribution to the cation-soil interactions has been estimated tentatively by using Born model of ion solvation. These values, when subtracted from the total quantities, yield the corresponding values of specific interaction, which have been rationalized. In addition, a simple linear relationship between Δ^O and Δ^o of K/Ca exchange has been pointed out.