Activated carbon (AC) surface may be modified by grafting amine-containing compounds to improve theudCO2 adsorption capacity. Two solid sorbents were prepared by anchoring a halogenated amine, i.e., 2-udchloroethylamine hydrochloric acid (CEA) on the surface of a microporous AC using a two-stageudmodification. At the first stage, the samples of AC were oxidized by nitric acid to increase the amount ofudoxygen surface groups and at the second stage, the oxidized samples were modified by anchoring CEA onudthe surface to produce a superior CO2 adsorbent. The oxidized samples were compared with the aid ofudproximate and ultimate analysis, nitrogen adsorption–desorption at �196 8C (77 K) and temperatureudprogrammed desorption (TPD) to decide on the best oxidation conditions. The amine-modified samplesudwere analyzed in terms of texture, surface chemistry and CO2 adsorption. The latter was studied usingudisothermal CO2 capture, temperature-programmed (TP) CO2 adsorption and cyclic operation. Theudmodified samples had a lower surface area than the parent sample. The best modified sample presentedudan increase of 45% in CO2 capture capacity at 100 8C. Based on unit surface area, the modified samplesudshowed great CO2 capture capacities, compared to the virgin sample. Moreover, the modified samplesudpresented a less dependency of CO2 capacity on temperature. This indicates that the adsorptionudmechanism shifts from physisorption to chemisorption by increasing temperature.
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