Surface complexation models (SCMs) have been successfully used to describe metal ion adsorption on pure mineral materials. However, such models have rarely been applied to model adsorption on natural materials. In this study, the surfacecomplexation model approach was used to describe the surface properties and adsorption behavior of natural aquatic sediment. Three typical versions of the surface complexation model were used: constant capacitance model (CCM), diffuse layer model (DLM),and triple layer model (TLM). All the model parameters were determined on the basis of the experimental data of the p0tentiometric titration and the metal adsorption isotherm using LeAn River (China) sediment. The experimental data of the adsorption edges were used to verify the performance of the models. This work indicated that all three models can simulate the experimental results very well. In predicting the adsorption behavior of the sediment sample, the relative errors of these three models werequite close. The results illustrate that SCMs can be used to successfully model natural materials.
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