Correlation of aqueous-phase adsorption isotherms

A correlation was developed to estimate the adsorption equilibrium capacity of various adsorbents and organic compounds using a combination of Polanyi potential theory and linear solvation energy relationships (LSERs). Polany i theory provided the basic mathematical form for the correlation. LSERs we re used to normalize the Polanyi theory based on the fundamental interactio n forces between the solvent, adsorbate, and adsorbent expected in aqueous- phase adsorption. The correlation was developed using 56 organic compounds and eight adsorbents. The following classes of organic compounds were used: (i) halogenated aliphatics, (ii) aromatics and halogenated aromatics, (iii ) polyfunctional organic compounds and (iv) sulfonated aromatics. The adsor bents were (i) three coal-based activated carbons (F-300, F-400, and APA), (ii) one coconut shell based activated carbon (580-26), (iii) one unspecifi ed activated carbon, and (iv) three synthetic polymeric adsorbents (XAD-4, XAD-7, and XEN-563). The proposed correlation, which considers the fundamen tal solvent-adsorbate-adsorbent interaction forces, showed a significant im provement in predicting the adsorption capacity over a correlation that con sidered only van der Waals forces. However, the correlations did not predic t the adsorption capacities of highly soluble organic compounds such as pol ysulfonated aromatics and polyfunctional organic compounds.