Effect of thermal oxidation of activated carbon surface on its adsorption towards dibenzothiophene

The effect of thermal oxidation of activated carbon (AC) on adsorption capacity of dibenzothiophene (DBT) was investigated. ACs were treated in air by thermal oxidation at different temperature 473, 573 and 673 K and thus modified ACs, AC₄₇₃, AC₅₇₃ and AC₆₇₃ were separately available. The oxygen functional groups on the surfaces of the ACs were determined separately by diffuse reflectance infrared Fourier transform spectroscopy and Boehm titration. The influence of the surface chemistry of the ACs on its adsorption towards DBT was discussed. The results showed that after the thermal oxidation of carbon surfaces, its total basicity decreased, while its total acidity increased. The higher the oxidation temperature was, the more the amounts of surface acidic oxygen-containing groups were, and thus the higher the amounts adsorbed of DBT on corresponding carbon were. For the original AC, AC₄₇₃, AC₅₇₃ and AC₆₇₃, the breakthrough amount of the treat fuel with containing 320 mg S l^-1 was 35.5, 45, 52.5 and 61 ml fuel g^-1 A^-1, respectively, corresponding to the breakthrough capacity of 11.4, 14.5, 16.8 and 19.5 mg of sulfur per gram of adsorbent (mg S g^-1 A^-1). The adsorption capacity of the AC₄₇₃, AC₅₇₃ and AC₆₇₃ for DBT increased separately by 27.2%, 47.4% and 70.2% compared to the original AC.