Modeling of divalent heavy metal ion adsorption on the surface of iron(III) oxide particles

Abstract

Soils and sediments contain metal oxide particles and control the concentration of heavy metal ions in natural waters at low levels by adsorption. The adsorption isotherms of divalent heavy metal ions on the surface of iron(III) oxide particles were obtained, and modeling of the adsorption reaction was made to describe and predict water quality. The model assumes (1) surface complex formation due to the (1:1) and (1: 2) cation exchange reactions with protons of acid surface hydroxyl sites and (2) suppression of the reactions by a linear increase in the Gibbs free energy change (AG) with the surface coverage. From the model parameters, it was found that the adsorption affinity increases in the order: Co2+≤Zn2+