Revisiting models of Cd, Cu, Pb and Zn adsorption onto Fe(III) oxides

Abstract A generic hydrous Fe oxide surface is often used in surface complexation modeling for predicting metal behavior in aqueous and soil environments. However, this approach may lead to incorrect results because there are many different naturally-occurring Fe(III) (oxyhydr)oxide mineral phases in the environment, each exhibiting distinct adsorption characteristics. This work presents a consistent dataset of surface complexation model parameters valid at 25 °C and 1 bar that characterize the adsorption of selected divalent metals (Cd, Cu, Pb, Zn) onto environmentally relevant Fe(III) (oxyhydr)oxides, i.e., FeOOH and Fe 2 O 3 polymorphs (goethite, hematite, lepidocrocite, maghemite), at varying metal concentrations and ionic strengths. The parameters were obtained using a simple and unified workflow and are readily implementable into widely used geochemical codes, such as Visual MINTEQ, MINEQL+, and ORCHESTRA, enabling quantification of metal adsorption onto a range of Fe(III) oxides in various aqueous environments.