Interaction between silver iodide surfaces in the presence of specifically adsorbed ions

Abstract

Interaction pressures between approaching identical semi-infinite plates are examined for AgI in aqueous solution in the cases of constant Ag⁺/I^– charge, constant total charge, constant wall potential ψ₀ and constant diffuse layer potential ψ_d. For this purpose the adsorption isotherm for K⁺ ions on silver iodide is taken from a combination of potentiometric titration and electrokinetic data. The physically unrealistic result of repulsive pressures tending to infinite values at short separations, which occurs for constant total charge, is shown not to occur for constant surface charge when the adsorbed charge due to indifferent counter ions can equilibrate on approach.