Interactions involved in the adsorption of aromatic compounds and heavy metals on ozonated activated carbon

摘要

The aim of the present work is to determine the role of dispersive and electrostatic interactions in the adsorption of aromatic compounds and heavy metals on activated carbon in aqueous phase. Naphthalenesulphonic acids, Cd(Ⅱ), Cr(Ⅲ) and Hg(Ⅱ) have been chosen to realise this work. A commercial activated carbon was treated with different ozone doses in order to obtain a series of carbon with increasing concentrations of surface oxygenated functional groups. The results obtained indicate that the adsorption process of aromatic compounds takes place mainly by p-p dispersion interactions between the aromatic ring electrons of the naphthalenesulphonic acids and those of the basal plane of the activated carbon. On the other hand, when Cd(Ⅱ) and Cr(Ⅲ) were used as adsorbates, the adsorption capacity and the affinity of the adsorbent augmented with the increase in acid-oxygenated groups on the activated carbon surface. These results imply that electrostatic-type interactions predominate in this adsorption process. The adsorption of Hg(Ⅱ) decreased with greater oxidation of the activated carbon. Oxygenated functional groups on carbon surface decreased the reductive properties of the activated carbon, therefore impeding the adsorptionreduction mechanism that determines the Hg(Ⅱ) adsorption.