Effect of chemical surface heterogeneity on the adsorption mechanism of dissolved aromatics on activated carbon

The effects of oxygen-containing groups, particularly carboxylic and carbon yl groups, on the adsorption of dissolved aromatics on ash-free activated c arbon have been studied. Adsorption isotherms for phenol, aniline, nitroben zene, and benzoic acid were generated in both aqueous and cyclohexane media , using carbons with different amounts of surface oxygen groups. It was fou nd that water adsorption, dispersive/repulsive interactions, and hydrogen-b onding were the main mechanisms by which surface oxygen groups influence th e adsorption capacity, while donor-acceptor interactions were found not to be significant. The adsorption mechanism was also found to be influenced by the properties of the functional group on the aromatic adsorbate, especial ly its ability to hydrogen-bond and through its activating/deactivating inf luence on the aromatic ring. (C) 2000 Elsevier Science Ltd. All rights rese rved.