Abstract
Influence of solvent and surface functional groups of adsorbents on the adsorption of dissolved aromatics onto activated carbons was examined using batch experiments at room temperature. Phenol and nitrobenzene were employed as aromatics adsorbates, water and hexane were used as solvents, and oxidized and out-gassed activated carbons were prepared as adsorbents. The oxidation of adsorbent was carried out by warming the carbon in nitric acid to introduce oxygen functional groups, and the out-gassed carbon was obtained by heating the oxidized carbon at 1273 K in helium flow to make oxygen free surface without altering the textural structure. Comparing the adsorption isotherms, the out-gassed activated carbon exhibited higher adsorption capacity than the oxidized counterpart in the aqueous solution, whereas the opposite results were obtained in case of the hexane solution. Though significant decrease in adsorption amount of nitrobenzene was observed switching from aqueous to hexane solution, it was not observed in the phenol adsorption. Based on the experimental results, not only adsorbate-adsorbent interaction but also adsorbent-solvent and adsorbate-solvent interactions were found to play important roles for the aromatics adsorption onto the activated carbons.
