A study of the adsorption of aromatic compounds using activated carbons prepared from chestnut shell

Activated carbons (ACs) prepared from chestnut shell were used as adsorbents for the removal of benzoic acid, salicylic acid and phenol from aqueous solutions. Adsorption studies were carried out by modifying activation temperature, concentration of activating acid and pH. The samples presented a microporous texture with acidic groups on the surface. It was found that the adsorption process not only depended on the porosity and the functional groups present in the AC, but was also affected by the solubility, the number and type of substituent groups, the superficial acidity in the adsorbate and the adsorbate-adsorbent interactions. The order of removal capacity was determined as follows: salicylic acid > benzoic acid > phenol. The differences in energy between the orbital frontier of the electronic densities of the adsorbent and the adsorbates, predicted by the HyperChem program, explained the experimental data pretty well.