Many environmentally significant synthetic aromatic compounds such as pentachlorophenol, benzene and naphthalene sulfonates, and benzene carboxylates exist as anions in water over a wide range of pH values. Understandably, both ionic charges andnonpolar moieties of these organic compounds govern their sorption characteristics. This study reports the results of very favorable sorption behaviors of these anthropogenic aromatic compounds onto polymeric anion exchangers. Such favorable sorptionequilibria are, however, distinctively unique because they are all endothermic processes and accompanied by high positive entropy changes. Solvent dielectric constant, polarity or moisture content of the ion-exchanger matrix, and the nonpolar moiety (NPM) of the aromatic anion are the three fundamental process variables which govern the overall sorption equilibrium. Anomalous enthalpic and entropic changes associated with such sorption processes are explained from a mechanistic viewpoint after taking intoconsideration appropriate NPM-solvent and NPM-matrix interactions. Experimental observations made in this study are quite analogous to the transfer of hydrophobic methane from self-associated, polar water phase to nonpolar cyclohexane phase.
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