Two different approaches of developing CO2 adsorbents were compared, i.e., by impregnating amines upon activated carbon concentrates from fly ash (PFA)-derived unburned carbon concentrates (PFA_ACC) and through the carbonization and subsequent activation of mixtures of sugar and nitrogen containing compounds. For the PFA__ACC, tetra-ethylene-penta-amine-acrylonitrile was a stronger CO2 adsorption enhancing amine than di-ethanolamine or poly-ethylenimine. Of the N-compounds mixed with the sugars, urea yielded the highest nitrogen content in the resulting carbons. However, carbazole, despite yielding the lowest nitrogen content, engendered the highest adsorption capacity both in terms of the overall amount of CO2 adsorbed by the sorbents and also the mass of CO2 adsorbed per square meter of their surface area. This indicated that it is not just the amount of nitrogen in the adsorbent, but also the nitrogen functionality that has a strong influence upon the performance of the carbons.