EVALUATION OF MULTICOMPONENT ADSORPTION EQUILIBRIA FOR ORGANIC MIXTURES ONTO ACTIVATED CARBON

Activated carbon adsorption isotherms were determined experimentally for mixtures containing specific synthetic organics and, in some instances, relatively uncharacterized background dissolved organic matter. Ideal adsorbed solution theory (IAST) was used to predict and/or describe competitive equilibria. Two models, the well-known Freundlich equation and an empirical three-parameter equation developed for this work, were used to describe single solute equilibria. As expected, the three-parameter model was able to more accurately describe single solute isotherms which deviated from log-log linearity. Comparisons were made of IAST calculations performed with the Freundlich versus the three-parameter equation and yielded mixed results, the interpretation of which may be influenced by the method chosen to quantify the goodness of fit. The system studied also exhibited variability in the degree of ideality with respect to solute-solute competition as evaluated by IAST. A modeling methodology which evaluated equilibrium parameters and modeled data in terms of the target compounds only provided a quantitative assessment of the impacts of unknown organic background on the adsorption capacity of the target species.