In order to enhance the selective adsorption of CO₂, the surface of granular activated carbon (GAC) was modified by an ammonia solution. Ammonia in an aqueous phase could be decomposed into NH4⁺, OH^- and other N-containing elements. The present work attempted to impregnate some basic functional groups leading to chemisorption of the activated carbon surface. While the addition of N-groups reduced the specific surface area from 2071.4 m²/g to about 1300-1400 m²/g, the adsorption capacity for CO₂ increased to a certain degree, and the best amination could be achieved with the reaction at 100℃ for 12 hours. The enhanced adsorption capacity could be obtained by formation of nitrogen functionalities such as amine, pyrrolic groups and pyridine oxides which were verified by XPS analysis.

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