The effect of thermal oxidation of activated carbon surface on its adsorption of dibenzothiophene was investigated. The surface oxidation of the activated carbon was carried out by heating at different temperatures in the air. Static equilibrium adsorption experiments were conducted to determine the isotherms of dibenzothiophene on the original and oxidized activated carbons. The type and concentration of oxygen functional groups on the activated carbons were determined by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and Boehm titration respectively. The influence of the surface chemistry of the activated carbons on the adsorption capacity for dibenzothiophene was discussed. The results showed that the acid oxygen-containing groups of the activated carbon surfaces played an important role in enhancing the adsorption of dibenzothiophene. It was shown that the use of thermal oxidation could increase the concentration of oxygen-containing groups on the activated carbon surfaces

and consequently increase its adsorption capacity for dibenzothiophene. It was also found that the higher the oxidation temperature

the more the oxygen-containing groups on activated carbon surface

which enhanced the adsorption capacity of dibenzothiophene on its surfaces. The Langmuir equation was shown to fit well these isotherms.