Diffuse sorption modeling: Ionic adsorption on silica

The Poisson–Boltzmann equation was applied to simulation of published data on adsorption of bivalent metal ions on silica. The surface charge of silica was approximated with the basic Stern model (without coordinate binding of sodium ions). It was found that the adsorption of alkaline-earth metal ions is closely consistent with the Poisson–Boltzmann equation; i.e., it may be completely explained by electrostatic attraction in the diffuse layer. Adsorption in the diffuse layer was also found important for some heavy metals, such as cadmium.

Adsorption of alkaline-earth metal ions on silica may be completely explained by electrostatic attraction in the diffuse layer.Figure optionsDownload high-quality image (121 K)Download as PowerPoint slideResearch highlights
► Composition of diffuse layer in arbitrary salt media may be calculated analytically.
► Adsorption of alkaline earth on silica is completely diffuse sorption.
► Diffuse sorption on silica is important for some heavy metals such as cadmium.