Competitive Adsorption of Phenols on GAC. I: Adsorption Equilibrium

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Abstract
The impact of the presence of molecular oxygen on multicomponent adsorption is evaluated in this study. Adsorption equilibria for binary mixtures of phenol/o‐cresol and ternary mixtures of phenol/o‐cresol/3‐ethylphenol on granular activated carbon (GAC) are determined at 23°C using three different initial‐concentration combinations. Experiments were conducted under conditions where molecular oxygen is present (oxic adsorption) and under conditions where oxygen was excluded from the adsorbate solution and the GAC particles (anoxic adsorption). The ideal adsorbed solution theory, using the Myers equation for correlating the single‐solute anoxic isotherms, is found to accurately describe the competitive adsorption behavior of these phenolic mixtures under anoxic conditions. When the Freundlich equation was used to describe the single solute behavior, increased deviations were observed. Poor model predictions for the oxic isotherms are attributed to the presence of molecular oxygen, which promotes the polymerization of the adsorbates on the surface of GAC.