Modeling adsorption in multicomponent systems using a Freundlich-type isotherm


The suitability of a Freundlich-type isotherm, the Sheindorf-Rebuhn-Sheintuch (SRS) equation, to represent the competitive adsorption of Sr, Cs and Co in Ca-montmorillonite suspensions was investigated. Experimental adsorption data were obtained for systems containing these cations as single-component, binary and ternary mixtures. The competition coefficient αij, which were obtained based on the experimental adsorption data for bicomponent systems, can be viewed as a way to quantify competitive interactions. The competition coefficients obtained for the cations under consideration indicate that their competitive interactions are of similar magnitude, with the cation least affected by competitive effects being Cs, while the adsorption of Co was more significantly affected by the presence of Cs, and Sr by the presence of Co. After αij-values were substituted in the SRS equation, the adsorption of systems of three or more components could be predicted. To validate the SRS equation, the adsorption values predicted by this equation for the ternary mixture SrCs Co were compared to values determined experimentally. The SRS equation successfully modeled adsorption for the range of concentrations that followed Freundlich behavior. © 1993.

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Journal of Contaminant Hydrology